11

Gastroenteritis amp Gastroenteritis amp Food PoisoningFood Poisoning

Dr Dr Thamina SayyedThamina Sayyed

Registrar ndash MicrobiologyRegistrar ndash Microbiology

KKUHKKUH

22

Foodborne DiseasesFoodborne DiseasesApply to illnesses acquired by consumption of Apply to illnesses acquired by consumption of contaminated foodcontaminated food

Sometimes incorrectly referred to as food poisoningSometimes incorrectly referred to as food poisoning

Includes Includes foodbornee intoxications foodbornee intoxications

foodbornee infectionsfoodbornee infections

GastroenteritisGastroenteritis Syndromes of diaeehea amp vomiting that tend to involve non Syndromes of diaeehea amp vomiting that tend to involve non

infalmmatory infection in the small bowel orinfalmmatory infection in the small bowel or

inflammatory infection of large boweleg EcoliYersinia inflammatory infection of large boweleg EcoliYersinia campylobacterclostridiumcryptosporidiumcyclosporarotavirus campylobacterclostridiumcryptosporidiumcyclosporarotavirus

etcetc

33

There are There are two types of food poisoningtwo types of food poisoning food infection and food intoxication food infection and food intoxication

1)Food infection1)Food infection you eat microbes and they grow in the gut and produce an

infection eg eg Campylobacter jejuni Salmonella spp Salmonella typhii Shigella spp Vibrio cholerae Vibrio parahemolyticus Vibrio vulnificus 2)2) Food intoxicationFood intoxication you eat food containing a toxin and that poison makes you sick (Staphylococcus aureus ) including bacterially produced exotoxinsincluding bacterially produced exotoxins

44

People at riskPeople at risk Food poisoning is more likely to affect people with

lowered resistance to disease than healthy people who might show mild symptoms or none at all

The following are particularly vulnerable to food

poisoning - - Elderly or sick people - Babies - Young children Pregnant women

55

Factors affecting microbial growth in foodbull

Time Moisture Food WarmthIntrinsic conditions present in food ndash Water availability (aw) amount of water in food

(pure water is 10)bull Most food gt098 most bacteria require gt090 ndash pH most pathogens not grow at pHlt45 (except

Lactic acid bacteria) ndash Nutrientsbull Extrinsic ndash Storage temperature lt0 0C no growth (water crystallizes) Refrigerator 4 C to 10 C (enzyme rxns very slow ⁰ ⁰

or non- existent ndash Atmosphere availability of O2

66

In ideal conditions where there is Moisture Food and Warmth (37degrees centigrade is ideal) bacteria can double every 10 to 20 minutes They do this by dividing in to two This is called

Binary Fission

77

SporeSpore

A A resting resistant phaseresting resistant phase of some bacteria (including of some bacteria (including

Clostridium Perfringens and Botulinum and Bacillus Cereus) Clostridium Perfringens and Botulinum and Bacillus Cereus)

The bacterium produces a protective coat which helps it to The bacterium produces a protective coat which helps it to

survive high temperatures (up to 120degC) and lack of water survive high temperatures (up to 120degC) and lack of water

When When favourable conditions return the spores split openfavourable conditions return the spores split open and and

releaserelease the bacteriathe bacteria which are then able to grow and multiply which are then able to grow and multiply

Spore forming inside cell

88

What Foods Are Most Likely to be What Foods Are Most Likely to be

ContaminatedContaminated raw meat and poultryraw meat and poultry

raw eggs (even in uncooked brownie cake or raw eggs (even in uncooked brownie cake or cookie dough)cookie dough)

unpasteurized milkunpasteurized milk

raw shellfishraw shellfish

unwashed raw fruits and vegetables unwashed raw fruits and vegetables

unpasteurized fruit juiceunpasteurized fruit juice

99

Sources of microbial contamination of foodSources of microbial contamination of food

Food handlerFood handler bad personal hygiene using same bad personal hygiene using same cutting board for meat amp vegetables knife cutting board for meat amp vegetables knife contaminated by bloodcontaminated by blood

Food processingFood processing equipment packaging personal contamination equipment packaging personal contamination

during processingduring processing

Food storageFood storage time amp temp time amp temp

Fecal contaminationFecal contamination in farms prior to collection in farms prior to collection

1010

Types of bacteriaTypes of bacteria

SpoilageSpoilage Not particularly harmful bacteria Not particularly harmful bacteria which cause food to go offwhich cause food to go off

BeneficialBeneficial ldquoGood Bacteriardquo which are used ldquoGood Bacteriardquo which are used to make yoghurt and cheeseto make yoghurt and cheese

PathogenicPathogenic Illness causing bacteria Illness causing bacteria

1111

Symptoms of Microbiological Symptoms of Microbiological Food PoisoningFood Poisoning

Infections require an incubation period ofgenerally 2 to 3 days Typical symptoms abdominal cramps diarrhea nausea buthellipthere can be harsher long-lasting effects

Intoxications are often immediate(sometimes with 20 minutes) with nauseaabdominal cramps and violent vomitingIllness is usually rather short-lived

1212

Symptoms of Symptoms of food poisoningfood poisoning

NauseaAbdominal pain

VomitingDiarrhea

GastroenteritisFever

Headache Fatigue

1313

Causes of foodborne diseaseCauses of foodborne disease

1414

What Are the What Are the Most CommonMost Common Causes of Causes of foodborne Illnessfoodborne Illness

Those caused by the bacteriaThose caused by the bacteriabull CampylobacterCampylobacterbull SalmonellaSalmonellabull E coli O157H7E coli O157H7

Those caused by a group of virusesThose caused by a group of virusesbull Norwalk and Norwalk-like viruses Norwalk and Norwalk-like viruses

1515

Infectious Non-infectiousInfectious Non-infectious

Bacterial Virus protozoaeBacterial Virus protozoae

Biological Biological NonbiologicalNonbiological

Causes of foodborne diseaseCauses of foodborne disease

1616

Infectious causes of food poisoningInfectious causes of food poisoning

BacteriaBacteria Salmonella species Campylobacter jejuni Staphylococcus aureus Clostridium perfringens Clostridium botulinum Bacillus and other sporing

bacilli Shigella species Ecoli Yersinia enterocolitica Vibrio parahaemolyticus Aeromonas hydrophilia Streptococcus species

Group C E and G The other eg Listeria

monocytogens

Virusesa- Hepatitis Ab- Hepatitis Ec- Smal lrounded structured viruses(SRSV)eg

Norovirus CalicivirusesAstrovirusesRotaviruses

Protozoae Protozoae 1- Giardiasis2- Amoebiasis3 Cryptosporiosis4- Isospora5- Balantidum6- Blastocytosis

hominis7- Microsporidia8- Toxoplasmosis

()

1717

Causes Of foodborneCauses Of foodborne

VirusesVirusesUnlike bacteria viruses do not multiply in FoodsAcquired by

a- Primary contamination From shell Fish From Oysters From Mussels From Vegetables eg Hepatitis A From Vegetables irrigated by untreated water

b- Secondary contamination From Food handlers eg Hepatitis A

1818

Non infective causes of food poisoning

Physical Physical contaminationcontamination- - objects falling in objects falling in to food ndash metal to food ndash metal glass packaging glass packaging materials etcmaterials etc

Chemical Chemical contaminationcontamination- - Bleach cleaning Bleach cleaning chemicals chemicals getting in to food getting in to food heavy metalsheavy metals

Natural Natural contaminationcontamination Poisonous plants Poisonous plants and berries and berries undercooked red undercooked red kidney beanskidney beans

Non biological Biological

1919

Causes of foodborne Diseases (ContinuedCauses of foodborne Diseases (Continued

Biological FromBiological Froma- Mushroomsa- Mushrooms

b- Harmful algal speciesb- Harmful algal species

c- Fish c- Fish egeg Ciguatera Fish poisoningCiguatera Fish poisoning Scombroid Fish poisoning associated with Scombroid Fish poisoning associated with

raised Histamine levelsraised Histamine levels Paralytic shell Fish poisoningParalytic shell Fish poisoning

2020

2121

bull 1- Bovine tuberculosis (milk)bull 2- Brucellosis (milk)bull 3- Toxoplasmosis (meat)bull 4- Listerosis (milk products)bull 5- Mad cow diseases virus etc

Some Diseases Which Are Transmitted By Some Diseases Which Are Transmitted By Food But Not Considered As Food Food But Not Considered As Food PoisoningPoisoning

2222

Exotoxins bull Produced inside bacteria and secreted ndash Enterotoxin Neurotoxin Cardiotoxin

bull Superantigen Type I1048774intense immune response1048774cytokines1048774fever nausea vomitting shock (Staph aureus)

bull Membrane disrupting toxin Type II1048774 lysis of cells by disrupting membrane

bull A-B toxins Type III has two parts ndash A is active enzyme toxin that inhibits protein

synthesis and kills cell ndash B binds to surface so toxin is transported across plasma membrane (Clostridium

2323

Selected Clinical and Epidemiologic Characteristics of Typical Illness Caused By Common foodbornee Pathogens

Pathogen Typical Incubation Period

Duration Typical Clinical Presentation

Assorted Foods

Bacterial Salmonella species

1-3 Days 4-7 Days Gastroenteritis Undercooked eggs or poultry produce

Campylobacter jejuni

2-5 Days 2-10 Days

Gastroenteritis Undercooked poultry unpasteurized

dairy products E coli Enterotoxigenic

1-3 Days 3-7 Days Gastroenteritis Many foods

Shigella species 1-2 Days 4-7 Days Gastroenteritis Produce egg salad

2424

Listeria monocytogenes

2-6 weeks Variable Gastroenteritis meningitis abortion

Deli meat hotdogs unpasteurized dairy products

Bacillus cereus 1-6 hour lt24 hour Vomiting Gastroenteritis

Fried rice meats

Clostridium botulinum

12-72 hour Days-months Blurred vision paralysis

Home-canned foods fermented fish

Staphylococcus aureus

1-6 hour 1-2 Days Gastroenteritis particularly nausea

Meats potato amp pork unpasteurized dairy products

Yersinia enterocolitica

1-2 Days 1-3 weeks Gastroenteritis appendicitis-like syndrome

Undercooked pork unpasteurized dairy products

2525

ViralViral Typical incubation period

Duration Typical clinical presentation

Assorted foods

Norovirus 1-2 Days 12-60 Hr Gastroenteritis

Under

cooked shellfish

Hepatitis A virus

15-50 Days

Weeks-months

Hepatitis Produce undercooked shellfish

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

22

Foodborne DiseasesFoodborne DiseasesApply to illnesses acquired by consumption of Apply to illnesses acquired by consumption of contaminated foodcontaminated food

Sometimes incorrectly referred to as food poisoningSometimes incorrectly referred to as food poisoning

Includes Includes foodbornee intoxications foodbornee intoxications

foodbornee infectionsfoodbornee infections

GastroenteritisGastroenteritis Syndromes of diaeehea amp vomiting that tend to involve non Syndromes of diaeehea amp vomiting that tend to involve non

infalmmatory infection in the small bowel orinfalmmatory infection in the small bowel or

inflammatory infection of large boweleg EcoliYersinia inflammatory infection of large boweleg EcoliYersinia campylobacterclostridiumcryptosporidiumcyclosporarotavirus campylobacterclostridiumcryptosporidiumcyclosporarotavirus

etcetc

33

There are There are two types of food poisoningtwo types of food poisoning food infection and food intoxication food infection and food intoxication

1)Food infection1)Food infection you eat microbes and they grow in the gut and produce an

infection eg eg Campylobacter jejuni Salmonella spp Salmonella typhii Shigella spp Vibrio cholerae Vibrio parahemolyticus Vibrio vulnificus 2)2) Food intoxicationFood intoxication you eat food containing a toxin and that poison makes you sick (Staphylococcus aureus ) including bacterially produced exotoxinsincluding bacterially produced exotoxins

44

People at riskPeople at risk Food poisoning is more likely to affect people with

lowered resistance to disease than healthy people who might show mild symptoms or none at all

The following are particularly vulnerable to food

poisoning - - Elderly or sick people - Babies - Young children Pregnant women

55

Factors affecting microbial growth in foodbull

Time Moisture Food WarmthIntrinsic conditions present in food ndash Water availability (aw) amount of water in food

(pure water is 10)bull Most food gt098 most bacteria require gt090 ndash pH most pathogens not grow at pHlt45 (except

Lactic acid bacteria) ndash Nutrientsbull Extrinsic ndash Storage temperature lt0 0C no growth (water crystallizes) Refrigerator 4 C to 10 C (enzyme rxns very slow ⁰ ⁰

or non- existent ndash Atmosphere availability of O2

66

In ideal conditions where there is Moisture Food and Warmth (37degrees centigrade is ideal) bacteria can double every 10 to 20 minutes They do this by dividing in to two This is called

Binary Fission

77

SporeSpore

A A resting resistant phaseresting resistant phase of some bacteria (including of some bacteria (including

Clostridium Perfringens and Botulinum and Bacillus Cereus) Clostridium Perfringens and Botulinum and Bacillus Cereus)

The bacterium produces a protective coat which helps it to The bacterium produces a protective coat which helps it to

survive high temperatures (up to 120degC) and lack of water survive high temperatures (up to 120degC) and lack of water

When When favourable conditions return the spores split openfavourable conditions return the spores split open and and

releaserelease the bacteriathe bacteria which are then able to grow and multiply which are then able to grow and multiply

Spore forming inside cell

88

What Foods Are Most Likely to be What Foods Are Most Likely to be

ContaminatedContaminated raw meat and poultryraw meat and poultry

raw eggs (even in uncooked brownie cake or raw eggs (even in uncooked brownie cake or cookie dough)cookie dough)

unpasteurized milkunpasteurized milk

raw shellfishraw shellfish

unwashed raw fruits and vegetables unwashed raw fruits and vegetables

unpasteurized fruit juiceunpasteurized fruit juice

99

Sources of microbial contamination of foodSources of microbial contamination of food

Food handlerFood handler bad personal hygiene using same bad personal hygiene using same cutting board for meat amp vegetables knife cutting board for meat amp vegetables knife contaminated by bloodcontaminated by blood

Food processingFood processing equipment packaging personal contamination equipment packaging personal contamination

during processingduring processing

Food storageFood storage time amp temp time amp temp

Fecal contaminationFecal contamination in farms prior to collection in farms prior to collection

1010

Types of bacteriaTypes of bacteria

SpoilageSpoilage Not particularly harmful bacteria Not particularly harmful bacteria which cause food to go offwhich cause food to go off

BeneficialBeneficial ldquoGood Bacteriardquo which are used ldquoGood Bacteriardquo which are used to make yoghurt and cheeseto make yoghurt and cheese

PathogenicPathogenic Illness causing bacteria Illness causing bacteria

1111

Symptoms of Microbiological Symptoms of Microbiological Food PoisoningFood Poisoning

Infections require an incubation period ofgenerally 2 to 3 days Typical symptoms abdominal cramps diarrhea nausea buthellipthere can be harsher long-lasting effects

Intoxications are often immediate(sometimes with 20 minutes) with nauseaabdominal cramps and violent vomitingIllness is usually rather short-lived

1212

Symptoms of Symptoms of food poisoningfood poisoning

NauseaAbdominal pain

VomitingDiarrhea

GastroenteritisFever

Headache Fatigue

1313

Causes of foodborne diseaseCauses of foodborne disease

1414

What Are the What Are the Most CommonMost Common Causes of Causes of foodborne Illnessfoodborne Illness

Those caused by the bacteriaThose caused by the bacteriabull CampylobacterCampylobacterbull SalmonellaSalmonellabull E coli O157H7E coli O157H7

Those caused by a group of virusesThose caused by a group of virusesbull Norwalk and Norwalk-like viruses Norwalk and Norwalk-like viruses

1515

Infectious Non-infectiousInfectious Non-infectious

Bacterial Virus protozoaeBacterial Virus protozoae

Biological Biological NonbiologicalNonbiological

Causes of foodborne diseaseCauses of foodborne disease

1616

Infectious causes of food poisoningInfectious causes of food poisoning

BacteriaBacteria Salmonella species Campylobacter jejuni Staphylococcus aureus Clostridium perfringens Clostridium botulinum Bacillus and other sporing

bacilli Shigella species Ecoli Yersinia enterocolitica Vibrio parahaemolyticus Aeromonas hydrophilia Streptococcus species

Group C E and G The other eg Listeria

monocytogens

Virusesa- Hepatitis Ab- Hepatitis Ec- Smal lrounded structured viruses(SRSV)eg

Norovirus CalicivirusesAstrovirusesRotaviruses

Protozoae Protozoae 1- Giardiasis2- Amoebiasis3 Cryptosporiosis4- Isospora5- Balantidum6- Blastocytosis

hominis7- Microsporidia8- Toxoplasmosis

()

1717

Causes Of foodborneCauses Of foodborne

VirusesVirusesUnlike bacteria viruses do not multiply in FoodsAcquired by

a- Primary contamination From shell Fish From Oysters From Mussels From Vegetables eg Hepatitis A From Vegetables irrigated by untreated water

b- Secondary contamination From Food handlers eg Hepatitis A

1818

Non infective causes of food poisoning

Physical Physical contaminationcontamination- - objects falling in objects falling in to food ndash metal to food ndash metal glass packaging glass packaging materials etcmaterials etc

Chemical Chemical contaminationcontamination- - Bleach cleaning Bleach cleaning chemicals chemicals getting in to food getting in to food heavy metalsheavy metals

Natural Natural contaminationcontamination Poisonous plants Poisonous plants and berries and berries undercooked red undercooked red kidney beanskidney beans

Non biological Biological

1919

Causes of foodborne Diseases (ContinuedCauses of foodborne Diseases (Continued

Biological FromBiological Froma- Mushroomsa- Mushrooms

b- Harmful algal speciesb- Harmful algal species

c- Fish c- Fish egeg Ciguatera Fish poisoningCiguatera Fish poisoning Scombroid Fish poisoning associated with Scombroid Fish poisoning associated with

raised Histamine levelsraised Histamine levels Paralytic shell Fish poisoningParalytic shell Fish poisoning

2020

2121

bull 1- Bovine tuberculosis (milk)bull 2- Brucellosis (milk)bull 3- Toxoplasmosis (meat)bull 4- Listerosis (milk products)bull 5- Mad cow diseases virus etc

Some Diseases Which Are Transmitted By Some Diseases Which Are Transmitted By Food But Not Considered As Food Food But Not Considered As Food PoisoningPoisoning

2222

Exotoxins bull Produced inside bacteria and secreted ndash Enterotoxin Neurotoxin Cardiotoxin

bull Superantigen Type I1048774intense immune response1048774cytokines1048774fever nausea vomitting shock (Staph aureus)

bull Membrane disrupting toxin Type II1048774 lysis of cells by disrupting membrane

bull A-B toxins Type III has two parts ndash A is active enzyme toxin that inhibits protein

synthesis and kills cell ndash B binds to surface so toxin is transported across plasma membrane (Clostridium

2323

Selected Clinical and Epidemiologic Characteristics of Typical Illness Caused By Common foodbornee Pathogens

Pathogen Typical Incubation Period

Duration Typical Clinical Presentation

Assorted Foods

Bacterial Salmonella species

1-3 Days 4-7 Days Gastroenteritis Undercooked eggs or poultry produce

Campylobacter jejuni

2-5 Days 2-10 Days

Gastroenteritis Undercooked poultry unpasteurized

dairy products E coli Enterotoxigenic

1-3 Days 3-7 Days Gastroenteritis Many foods

Shigella species 1-2 Days 4-7 Days Gastroenteritis Produce egg salad

2424

Listeria monocytogenes

2-6 weeks Variable Gastroenteritis meningitis abortion

Deli meat hotdogs unpasteurized dairy products

Bacillus cereus 1-6 hour lt24 hour Vomiting Gastroenteritis

Fried rice meats

Clostridium botulinum

12-72 hour Days-months Blurred vision paralysis

Home-canned foods fermented fish

Staphylococcus aureus

1-6 hour 1-2 Days Gastroenteritis particularly nausea

Meats potato amp pork unpasteurized dairy products

Yersinia enterocolitica

1-2 Days 1-3 weeks Gastroenteritis appendicitis-like syndrome

Undercooked pork unpasteurized dairy products

2525

ViralViral Typical incubation period

Duration Typical clinical presentation

Assorted foods

Norovirus 1-2 Days 12-60 Hr Gastroenteritis

Under

cooked shellfish

Hepatitis A virus

15-50 Days

Weeks-months

Hepatitis Produce undercooked shellfish

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

33

There are There are two types of food poisoningtwo types of food poisoning food infection and food intoxication food infection and food intoxication

1)Food infection1)Food infection you eat microbes and they grow in the gut and produce an

infection eg eg Campylobacter jejuni Salmonella spp Salmonella typhii Shigella spp Vibrio cholerae Vibrio parahemolyticus Vibrio vulnificus 2)2) Food intoxicationFood intoxication you eat food containing a toxin and that poison makes you sick (Staphylococcus aureus ) including bacterially produced exotoxinsincluding bacterially produced exotoxins

44

People at riskPeople at risk Food poisoning is more likely to affect people with

lowered resistance to disease than healthy people who might show mild symptoms or none at all

The following are particularly vulnerable to food

poisoning - - Elderly or sick people - Babies - Young children Pregnant women

55

Factors affecting microbial growth in foodbull

Time Moisture Food WarmthIntrinsic conditions present in food ndash Water availability (aw) amount of water in food

(pure water is 10)bull Most food gt098 most bacteria require gt090 ndash pH most pathogens not grow at pHlt45 (except

Lactic acid bacteria) ndash Nutrientsbull Extrinsic ndash Storage temperature lt0 0C no growth (water crystallizes) Refrigerator 4 C to 10 C (enzyme rxns very slow ⁰ ⁰

or non- existent ndash Atmosphere availability of O2

66

In ideal conditions where there is Moisture Food and Warmth (37degrees centigrade is ideal) bacteria can double every 10 to 20 minutes They do this by dividing in to two This is called

Binary Fission

77

SporeSpore

A A resting resistant phaseresting resistant phase of some bacteria (including of some bacteria (including

Clostridium Perfringens and Botulinum and Bacillus Cereus) Clostridium Perfringens and Botulinum and Bacillus Cereus)

The bacterium produces a protective coat which helps it to The bacterium produces a protective coat which helps it to

survive high temperatures (up to 120degC) and lack of water survive high temperatures (up to 120degC) and lack of water

When When favourable conditions return the spores split openfavourable conditions return the spores split open and and

releaserelease the bacteriathe bacteria which are then able to grow and multiply which are then able to grow and multiply

Spore forming inside cell

88

What Foods Are Most Likely to be What Foods Are Most Likely to be

ContaminatedContaminated raw meat and poultryraw meat and poultry

raw eggs (even in uncooked brownie cake or raw eggs (even in uncooked brownie cake or cookie dough)cookie dough)

unpasteurized milkunpasteurized milk

raw shellfishraw shellfish

unwashed raw fruits and vegetables unwashed raw fruits and vegetables

unpasteurized fruit juiceunpasteurized fruit juice

99

Sources of microbial contamination of foodSources of microbial contamination of food

Food handlerFood handler bad personal hygiene using same bad personal hygiene using same cutting board for meat amp vegetables knife cutting board for meat amp vegetables knife contaminated by bloodcontaminated by blood

Food processingFood processing equipment packaging personal contamination equipment packaging personal contamination

during processingduring processing

Food storageFood storage time amp temp time amp temp

Fecal contaminationFecal contamination in farms prior to collection in farms prior to collection

1010

Types of bacteriaTypes of bacteria

SpoilageSpoilage Not particularly harmful bacteria Not particularly harmful bacteria which cause food to go offwhich cause food to go off

BeneficialBeneficial ldquoGood Bacteriardquo which are used ldquoGood Bacteriardquo which are used to make yoghurt and cheeseto make yoghurt and cheese

PathogenicPathogenic Illness causing bacteria Illness causing bacteria

1111

Symptoms of Microbiological Symptoms of Microbiological Food PoisoningFood Poisoning

Infections require an incubation period ofgenerally 2 to 3 days Typical symptoms abdominal cramps diarrhea nausea buthellipthere can be harsher long-lasting effects

Intoxications are often immediate(sometimes with 20 minutes) with nauseaabdominal cramps and violent vomitingIllness is usually rather short-lived

1212

Symptoms of Symptoms of food poisoningfood poisoning

NauseaAbdominal pain

VomitingDiarrhea

GastroenteritisFever

Headache Fatigue

1313

Causes of foodborne diseaseCauses of foodborne disease

1414

What Are the What Are the Most CommonMost Common Causes of Causes of foodborne Illnessfoodborne Illness

Those caused by the bacteriaThose caused by the bacteriabull CampylobacterCampylobacterbull SalmonellaSalmonellabull E coli O157H7E coli O157H7

Those caused by a group of virusesThose caused by a group of virusesbull Norwalk and Norwalk-like viruses Norwalk and Norwalk-like viruses

1515

Infectious Non-infectiousInfectious Non-infectious

Bacterial Virus protozoaeBacterial Virus protozoae

Biological Biological NonbiologicalNonbiological

Causes of foodborne diseaseCauses of foodborne disease

1616

Infectious causes of food poisoningInfectious causes of food poisoning

BacteriaBacteria Salmonella species Campylobacter jejuni Staphylococcus aureus Clostridium perfringens Clostridium botulinum Bacillus and other sporing

bacilli Shigella species Ecoli Yersinia enterocolitica Vibrio parahaemolyticus Aeromonas hydrophilia Streptococcus species

Group C E and G The other eg Listeria

monocytogens

Virusesa- Hepatitis Ab- Hepatitis Ec- Smal lrounded structured viruses(SRSV)eg

Norovirus CalicivirusesAstrovirusesRotaviruses

Protozoae Protozoae 1- Giardiasis2- Amoebiasis3 Cryptosporiosis4- Isospora5- Balantidum6- Blastocytosis

hominis7- Microsporidia8- Toxoplasmosis

()

1717

Causes Of foodborneCauses Of foodborne

VirusesVirusesUnlike bacteria viruses do not multiply in FoodsAcquired by

a- Primary contamination From shell Fish From Oysters From Mussels From Vegetables eg Hepatitis A From Vegetables irrigated by untreated water

b- Secondary contamination From Food handlers eg Hepatitis A

1818

Non infective causes of food poisoning

Physical Physical contaminationcontamination- - objects falling in objects falling in to food ndash metal to food ndash metal glass packaging glass packaging materials etcmaterials etc

Chemical Chemical contaminationcontamination- - Bleach cleaning Bleach cleaning chemicals chemicals getting in to food getting in to food heavy metalsheavy metals

Natural Natural contaminationcontamination Poisonous plants Poisonous plants and berries and berries undercooked red undercooked red kidney beanskidney beans

Non biological Biological

1919

Causes of foodborne Diseases (ContinuedCauses of foodborne Diseases (Continued

Biological FromBiological Froma- Mushroomsa- Mushrooms

b- Harmful algal speciesb- Harmful algal species

c- Fish c- Fish egeg Ciguatera Fish poisoningCiguatera Fish poisoning Scombroid Fish poisoning associated with Scombroid Fish poisoning associated with

raised Histamine levelsraised Histamine levels Paralytic shell Fish poisoningParalytic shell Fish poisoning

2020

2121

bull 1- Bovine tuberculosis (milk)bull 2- Brucellosis (milk)bull 3- Toxoplasmosis (meat)bull 4- Listerosis (milk products)bull 5- Mad cow diseases virus etc

Some Diseases Which Are Transmitted By Some Diseases Which Are Transmitted By Food But Not Considered As Food Food But Not Considered As Food PoisoningPoisoning

2222

Exotoxins bull Produced inside bacteria and secreted ndash Enterotoxin Neurotoxin Cardiotoxin

bull Superantigen Type I1048774intense immune response1048774cytokines1048774fever nausea vomitting shock (Staph aureus)

bull Membrane disrupting toxin Type II1048774 lysis of cells by disrupting membrane

bull A-B toxins Type III has two parts ndash A is active enzyme toxin that inhibits protein

synthesis and kills cell ndash B binds to surface so toxin is transported across plasma membrane (Clostridium

2323

Selected Clinical and Epidemiologic Characteristics of Typical Illness Caused By Common foodbornee Pathogens

Pathogen Typical Incubation Period

Duration Typical Clinical Presentation

Assorted Foods

Bacterial Salmonella species

1-3 Days 4-7 Days Gastroenteritis Undercooked eggs or poultry produce

Campylobacter jejuni

2-5 Days 2-10 Days

Gastroenteritis Undercooked poultry unpasteurized

dairy products E coli Enterotoxigenic

1-3 Days 3-7 Days Gastroenteritis Many foods

Shigella species 1-2 Days 4-7 Days Gastroenteritis Produce egg salad

2424

Listeria monocytogenes

2-6 weeks Variable Gastroenteritis meningitis abortion

Deli meat hotdogs unpasteurized dairy products

Bacillus cereus 1-6 hour lt24 hour Vomiting Gastroenteritis

Fried rice meats

Clostridium botulinum

12-72 hour Days-months Blurred vision paralysis

Home-canned foods fermented fish

Staphylococcus aureus

1-6 hour 1-2 Days Gastroenteritis particularly nausea

Meats potato amp pork unpasteurized dairy products

Yersinia enterocolitica

1-2 Days 1-3 weeks Gastroenteritis appendicitis-like syndrome

Undercooked pork unpasteurized dairy products

2525

ViralViral Typical incubation period

Duration Typical clinical presentation

Assorted foods

Norovirus 1-2 Days 12-60 Hr Gastroenteritis

Under

cooked shellfish

Hepatitis A virus

15-50 Days

Weeks-months

Hepatitis Produce undercooked shellfish

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

44

People at riskPeople at risk Food poisoning is more likely to affect people with

lowered resistance to disease than healthy people who might show mild symptoms or none at all

The following are particularly vulnerable to food

poisoning - - Elderly or sick people - Babies - Young children Pregnant women

55

Factors affecting microbial growth in foodbull

Time Moisture Food WarmthIntrinsic conditions present in food ndash Water availability (aw) amount of water in food

(pure water is 10)bull Most food gt098 most bacteria require gt090 ndash pH most pathogens not grow at pHlt45 (except

Lactic acid bacteria) ndash Nutrientsbull Extrinsic ndash Storage temperature lt0 0C no growth (water crystallizes) Refrigerator 4 C to 10 C (enzyme rxns very slow ⁰ ⁰

or non- existent ndash Atmosphere availability of O2

66

In ideal conditions where there is Moisture Food and Warmth (37degrees centigrade is ideal) bacteria can double every 10 to 20 minutes They do this by dividing in to two This is called

Binary Fission

77

SporeSpore

A A resting resistant phaseresting resistant phase of some bacteria (including of some bacteria (including

Clostridium Perfringens and Botulinum and Bacillus Cereus) Clostridium Perfringens and Botulinum and Bacillus Cereus)

The bacterium produces a protective coat which helps it to The bacterium produces a protective coat which helps it to

survive high temperatures (up to 120degC) and lack of water survive high temperatures (up to 120degC) and lack of water

When When favourable conditions return the spores split openfavourable conditions return the spores split open and and

releaserelease the bacteriathe bacteria which are then able to grow and multiply which are then able to grow and multiply

Spore forming inside cell

88

What Foods Are Most Likely to be What Foods Are Most Likely to be

ContaminatedContaminated raw meat and poultryraw meat and poultry

raw eggs (even in uncooked brownie cake or raw eggs (even in uncooked brownie cake or cookie dough)cookie dough)

unpasteurized milkunpasteurized milk

raw shellfishraw shellfish

unwashed raw fruits and vegetables unwashed raw fruits and vegetables

unpasteurized fruit juiceunpasteurized fruit juice

99

Sources of microbial contamination of foodSources of microbial contamination of food

Food handlerFood handler bad personal hygiene using same bad personal hygiene using same cutting board for meat amp vegetables knife cutting board for meat amp vegetables knife contaminated by bloodcontaminated by blood

Food processingFood processing equipment packaging personal contamination equipment packaging personal contamination

during processingduring processing

Food storageFood storage time amp temp time amp temp

Fecal contaminationFecal contamination in farms prior to collection in farms prior to collection

1010

Types of bacteriaTypes of bacteria

SpoilageSpoilage Not particularly harmful bacteria Not particularly harmful bacteria which cause food to go offwhich cause food to go off

BeneficialBeneficial ldquoGood Bacteriardquo which are used ldquoGood Bacteriardquo which are used to make yoghurt and cheeseto make yoghurt and cheese

PathogenicPathogenic Illness causing bacteria Illness causing bacteria

1111

Symptoms of Microbiological Symptoms of Microbiological Food PoisoningFood Poisoning

Infections require an incubation period ofgenerally 2 to 3 days Typical symptoms abdominal cramps diarrhea nausea buthellipthere can be harsher long-lasting effects

Intoxications are often immediate(sometimes with 20 minutes) with nauseaabdominal cramps and violent vomitingIllness is usually rather short-lived

1212

Symptoms of Symptoms of food poisoningfood poisoning

NauseaAbdominal pain

VomitingDiarrhea

GastroenteritisFever

Headache Fatigue

1313

Causes of foodborne diseaseCauses of foodborne disease

1414

What Are the What Are the Most CommonMost Common Causes of Causes of foodborne Illnessfoodborne Illness

Those caused by the bacteriaThose caused by the bacteriabull CampylobacterCampylobacterbull SalmonellaSalmonellabull E coli O157H7E coli O157H7

Those caused by a group of virusesThose caused by a group of virusesbull Norwalk and Norwalk-like viruses Norwalk and Norwalk-like viruses

1515

Infectious Non-infectiousInfectious Non-infectious

Bacterial Virus protozoaeBacterial Virus protozoae

Biological Biological NonbiologicalNonbiological

Causes of foodborne diseaseCauses of foodborne disease

1616

Infectious causes of food poisoningInfectious causes of food poisoning

BacteriaBacteria Salmonella species Campylobacter jejuni Staphylococcus aureus Clostridium perfringens Clostridium botulinum Bacillus and other sporing

bacilli Shigella species Ecoli Yersinia enterocolitica Vibrio parahaemolyticus Aeromonas hydrophilia Streptococcus species

Group C E and G The other eg Listeria

monocytogens

Virusesa- Hepatitis Ab- Hepatitis Ec- Smal lrounded structured viruses(SRSV)eg

Norovirus CalicivirusesAstrovirusesRotaviruses

Protozoae Protozoae 1- Giardiasis2- Amoebiasis3 Cryptosporiosis4- Isospora5- Balantidum6- Blastocytosis

hominis7- Microsporidia8- Toxoplasmosis

()

1717

Causes Of foodborneCauses Of foodborne

VirusesVirusesUnlike bacteria viruses do not multiply in FoodsAcquired by

a- Primary contamination From shell Fish From Oysters From Mussels From Vegetables eg Hepatitis A From Vegetables irrigated by untreated water

b- Secondary contamination From Food handlers eg Hepatitis A

1818

Non infective causes of food poisoning

Physical Physical contaminationcontamination- - objects falling in objects falling in to food ndash metal to food ndash metal glass packaging glass packaging materials etcmaterials etc

Chemical Chemical contaminationcontamination- - Bleach cleaning Bleach cleaning chemicals chemicals getting in to food getting in to food heavy metalsheavy metals

Natural Natural contaminationcontamination Poisonous plants Poisonous plants and berries and berries undercooked red undercooked red kidney beanskidney beans

Non biological Biological

1919

Causes of foodborne Diseases (ContinuedCauses of foodborne Diseases (Continued

Biological FromBiological Froma- Mushroomsa- Mushrooms

b- Harmful algal speciesb- Harmful algal species

c- Fish c- Fish egeg Ciguatera Fish poisoningCiguatera Fish poisoning Scombroid Fish poisoning associated with Scombroid Fish poisoning associated with

raised Histamine levelsraised Histamine levels Paralytic shell Fish poisoningParalytic shell Fish poisoning

2020

2121

bull 1- Bovine tuberculosis (milk)bull 2- Brucellosis (milk)bull 3- Toxoplasmosis (meat)bull 4- Listerosis (milk products)bull 5- Mad cow diseases virus etc

Some Diseases Which Are Transmitted By Some Diseases Which Are Transmitted By Food But Not Considered As Food Food But Not Considered As Food PoisoningPoisoning

2222

Exotoxins bull Produced inside bacteria and secreted ndash Enterotoxin Neurotoxin Cardiotoxin

bull Superantigen Type I1048774intense immune response1048774cytokines1048774fever nausea vomitting shock (Staph aureus)

bull Membrane disrupting toxin Type II1048774 lysis of cells by disrupting membrane

bull A-B toxins Type III has two parts ndash A is active enzyme toxin that inhibits protein

synthesis and kills cell ndash B binds to surface so toxin is transported across plasma membrane (Clostridium

2323

Selected Clinical and Epidemiologic Characteristics of Typical Illness Caused By Common foodbornee Pathogens

Pathogen Typical Incubation Period

Duration Typical Clinical Presentation

Assorted Foods

Bacterial Salmonella species

1-3 Days 4-7 Days Gastroenteritis Undercooked eggs or poultry produce

Campylobacter jejuni

2-5 Days 2-10 Days

Gastroenteritis Undercooked poultry unpasteurized

dairy products E coli Enterotoxigenic

1-3 Days 3-7 Days Gastroenteritis Many foods

Shigella species 1-2 Days 4-7 Days Gastroenteritis Produce egg salad

2424

Listeria monocytogenes

2-6 weeks Variable Gastroenteritis meningitis abortion

Deli meat hotdogs unpasteurized dairy products

Bacillus cereus 1-6 hour lt24 hour Vomiting Gastroenteritis

Fried rice meats

Clostridium botulinum

12-72 hour Days-months Blurred vision paralysis

Home-canned foods fermented fish

Staphylococcus aureus

1-6 hour 1-2 Days Gastroenteritis particularly nausea

Meats potato amp pork unpasteurized dairy products

Yersinia enterocolitica

1-2 Days 1-3 weeks Gastroenteritis appendicitis-like syndrome

Undercooked pork unpasteurized dairy products

2525

ViralViral Typical incubation period

Duration Typical clinical presentation

Assorted foods

Norovirus 1-2 Days 12-60 Hr Gastroenteritis

Under

cooked shellfish

Hepatitis A virus

15-50 Days

Weeks-months

Hepatitis Produce undercooked shellfish

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

55

Factors affecting microbial growth in foodbull

Time Moisture Food WarmthIntrinsic conditions present in food ndash Water availability (aw) amount of water in food

(pure water is 10)bull Most food gt098 most bacteria require gt090 ndash pH most pathogens not grow at pHlt45 (except

Lactic acid bacteria) ndash Nutrientsbull Extrinsic ndash Storage temperature lt0 0C no growth (water crystallizes) Refrigerator 4 C to 10 C (enzyme rxns very slow ⁰ ⁰

or non- existent ndash Atmosphere availability of O2

66

In ideal conditions where there is Moisture Food and Warmth (37degrees centigrade is ideal) bacteria can double every 10 to 20 minutes They do this by dividing in to two This is called

Binary Fission

77

SporeSpore

A A resting resistant phaseresting resistant phase of some bacteria (including of some bacteria (including

Clostridium Perfringens and Botulinum and Bacillus Cereus) Clostridium Perfringens and Botulinum and Bacillus Cereus)

The bacterium produces a protective coat which helps it to The bacterium produces a protective coat which helps it to

survive high temperatures (up to 120degC) and lack of water survive high temperatures (up to 120degC) and lack of water

When When favourable conditions return the spores split openfavourable conditions return the spores split open and and

releaserelease the bacteriathe bacteria which are then able to grow and multiply which are then able to grow and multiply

Spore forming inside cell

88

What Foods Are Most Likely to be What Foods Are Most Likely to be

ContaminatedContaminated raw meat and poultryraw meat and poultry

raw eggs (even in uncooked brownie cake or raw eggs (even in uncooked brownie cake or cookie dough)cookie dough)

unpasteurized milkunpasteurized milk

raw shellfishraw shellfish

unwashed raw fruits and vegetables unwashed raw fruits and vegetables

unpasteurized fruit juiceunpasteurized fruit juice

99

Sources of microbial contamination of foodSources of microbial contamination of food

Food handlerFood handler bad personal hygiene using same bad personal hygiene using same cutting board for meat amp vegetables knife cutting board for meat amp vegetables knife contaminated by bloodcontaminated by blood

Food processingFood processing equipment packaging personal contamination equipment packaging personal contamination

during processingduring processing

Food storageFood storage time amp temp time amp temp

Fecal contaminationFecal contamination in farms prior to collection in farms prior to collection

1010

Types of bacteriaTypes of bacteria

SpoilageSpoilage Not particularly harmful bacteria Not particularly harmful bacteria which cause food to go offwhich cause food to go off

BeneficialBeneficial ldquoGood Bacteriardquo which are used ldquoGood Bacteriardquo which are used to make yoghurt and cheeseto make yoghurt and cheese

PathogenicPathogenic Illness causing bacteria Illness causing bacteria

1111

Symptoms of Microbiological Symptoms of Microbiological Food PoisoningFood Poisoning

Infections require an incubation period ofgenerally 2 to 3 days Typical symptoms abdominal cramps diarrhea nausea buthellipthere can be harsher long-lasting effects

Intoxications are often immediate(sometimes with 20 minutes) with nauseaabdominal cramps and violent vomitingIllness is usually rather short-lived

1212

Symptoms of Symptoms of food poisoningfood poisoning

NauseaAbdominal pain

VomitingDiarrhea

GastroenteritisFever

Headache Fatigue

1313

Causes of foodborne diseaseCauses of foodborne disease

1414

What Are the What Are the Most CommonMost Common Causes of Causes of foodborne Illnessfoodborne Illness

Those caused by the bacteriaThose caused by the bacteriabull CampylobacterCampylobacterbull SalmonellaSalmonellabull E coli O157H7E coli O157H7

Those caused by a group of virusesThose caused by a group of virusesbull Norwalk and Norwalk-like viruses Norwalk and Norwalk-like viruses

1515

Infectious Non-infectiousInfectious Non-infectious

Bacterial Virus protozoaeBacterial Virus protozoae

Biological Biological NonbiologicalNonbiological

Causes of foodborne diseaseCauses of foodborne disease

1616

Infectious causes of food poisoningInfectious causes of food poisoning

BacteriaBacteria Salmonella species Campylobacter jejuni Staphylococcus aureus Clostridium perfringens Clostridium botulinum Bacillus and other sporing

bacilli Shigella species Ecoli Yersinia enterocolitica Vibrio parahaemolyticus Aeromonas hydrophilia Streptococcus species

Group C E and G The other eg Listeria

monocytogens

Virusesa- Hepatitis Ab- Hepatitis Ec- Smal lrounded structured viruses(SRSV)eg

Norovirus CalicivirusesAstrovirusesRotaviruses

Protozoae Protozoae 1- Giardiasis2- Amoebiasis3 Cryptosporiosis4- Isospora5- Balantidum6- Blastocytosis

hominis7- Microsporidia8- Toxoplasmosis

()

1717

Causes Of foodborneCauses Of foodborne

VirusesVirusesUnlike bacteria viruses do not multiply in FoodsAcquired by

a- Primary contamination From shell Fish From Oysters From Mussels From Vegetables eg Hepatitis A From Vegetables irrigated by untreated water

b- Secondary contamination From Food handlers eg Hepatitis A

1818

Non infective causes of food poisoning

Physical Physical contaminationcontamination- - objects falling in objects falling in to food ndash metal to food ndash metal glass packaging glass packaging materials etcmaterials etc

Chemical Chemical contaminationcontamination- - Bleach cleaning Bleach cleaning chemicals chemicals getting in to food getting in to food heavy metalsheavy metals

Natural Natural contaminationcontamination Poisonous plants Poisonous plants and berries and berries undercooked red undercooked red kidney beanskidney beans

Non biological Biological

1919

Causes of foodborne Diseases (ContinuedCauses of foodborne Diseases (Continued

Biological FromBiological Froma- Mushroomsa- Mushrooms

b- Harmful algal speciesb- Harmful algal species

c- Fish c- Fish egeg Ciguatera Fish poisoningCiguatera Fish poisoning Scombroid Fish poisoning associated with Scombroid Fish poisoning associated with

raised Histamine levelsraised Histamine levels Paralytic shell Fish poisoningParalytic shell Fish poisoning

2020

2121

bull 1- Bovine tuberculosis (milk)bull 2- Brucellosis (milk)bull 3- Toxoplasmosis (meat)bull 4- Listerosis (milk products)bull 5- Mad cow diseases virus etc

Some Diseases Which Are Transmitted By Some Diseases Which Are Transmitted By Food But Not Considered As Food Food But Not Considered As Food PoisoningPoisoning

2222

Exotoxins bull Produced inside bacteria and secreted ndash Enterotoxin Neurotoxin Cardiotoxin

bull Superantigen Type I1048774intense immune response1048774cytokines1048774fever nausea vomitting shock (Staph aureus)

bull Membrane disrupting toxin Type II1048774 lysis of cells by disrupting membrane

bull A-B toxins Type III has two parts ndash A is active enzyme toxin that inhibits protein

synthesis and kills cell ndash B binds to surface so toxin is transported across plasma membrane (Clostridium

2323

Selected Clinical and Epidemiologic Characteristics of Typical Illness Caused By Common foodbornee Pathogens

Pathogen Typical Incubation Period

Duration Typical Clinical Presentation

Assorted Foods

Bacterial Salmonella species

1-3 Days 4-7 Days Gastroenteritis Undercooked eggs or poultry produce

Campylobacter jejuni

2-5 Days 2-10 Days

Gastroenteritis Undercooked poultry unpasteurized

dairy products E coli Enterotoxigenic

1-3 Days 3-7 Days Gastroenteritis Many foods

Shigella species 1-2 Days 4-7 Days Gastroenteritis Produce egg salad

2424

Listeria monocytogenes

2-6 weeks Variable Gastroenteritis meningitis abortion

Deli meat hotdogs unpasteurized dairy products

Bacillus cereus 1-6 hour lt24 hour Vomiting Gastroenteritis

Fried rice meats

Clostridium botulinum

12-72 hour Days-months Blurred vision paralysis

Home-canned foods fermented fish

Staphylococcus aureus

1-6 hour 1-2 Days Gastroenteritis particularly nausea

Meats potato amp pork unpasteurized dairy products

Yersinia enterocolitica

1-2 Days 1-3 weeks Gastroenteritis appendicitis-like syndrome

Undercooked pork unpasteurized dairy products

2525

ViralViral Typical incubation period

Duration Typical clinical presentation

Assorted foods

Norovirus 1-2 Days 12-60 Hr Gastroenteritis

Under

cooked shellfish

Hepatitis A virus

15-50 Days

Weeks-months

Hepatitis Produce undercooked shellfish

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

66

In ideal conditions where there is Moisture Food and Warmth (37degrees centigrade is ideal) bacteria can double every 10 to 20 minutes They do this by dividing in to two This is called

Binary Fission

77

SporeSpore

A A resting resistant phaseresting resistant phase of some bacteria (including of some bacteria (including

Clostridium Perfringens and Botulinum and Bacillus Cereus) Clostridium Perfringens and Botulinum and Bacillus Cereus)

The bacterium produces a protective coat which helps it to The bacterium produces a protective coat which helps it to

survive high temperatures (up to 120degC) and lack of water survive high temperatures (up to 120degC) and lack of water

When When favourable conditions return the spores split openfavourable conditions return the spores split open and and

releaserelease the bacteriathe bacteria which are then able to grow and multiply which are then able to grow and multiply

Spore forming inside cell

88

What Foods Are Most Likely to be What Foods Are Most Likely to be

ContaminatedContaminated raw meat and poultryraw meat and poultry

raw eggs (even in uncooked brownie cake or raw eggs (even in uncooked brownie cake or cookie dough)cookie dough)

unpasteurized milkunpasteurized milk

raw shellfishraw shellfish

unwashed raw fruits and vegetables unwashed raw fruits and vegetables

unpasteurized fruit juiceunpasteurized fruit juice

99

Sources of microbial contamination of foodSources of microbial contamination of food

Food handlerFood handler bad personal hygiene using same bad personal hygiene using same cutting board for meat amp vegetables knife cutting board for meat amp vegetables knife contaminated by bloodcontaminated by blood

Food processingFood processing equipment packaging personal contamination equipment packaging personal contamination

during processingduring processing

Food storageFood storage time amp temp time amp temp

Fecal contaminationFecal contamination in farms prior to collection in farms prior to collection

1010

Types of bacteriaTypes of bacteria

SpoilageSpoilage Not particularly harmful bacteria Not particularly harmful bacteria which cause food to go offwhich cause food to go off

BeneficialBeneficial ldquoGood Bacteriardquo which are used ldquoGood Bacteriardquo which are used to make yoghurt and cheeseto make yoghurt and cheese

PathogenicPathogenic Illness causing bacteria Illness causing bacteria

1111

Symptoms of Microbiological Symptoms of Microbiological Food PoisoningFood Poisoning

Infections require an incubation period ofgenerally 2 to 3 days Typical symptoms abdominal cramps diarrhea nausea buthellipthere can be harsher long-lasting effects

Intoxications are often immediate(sometimes with 20 minutes) with nauseaabdominal cramps and violent vomitingIllness is usually rather short-lived

1212

Symptoms of Symptoms of food poisoningfood poisoning

NauseaAbdominal pain

VomitingDiarrhea

GastroenteritisFever

Headache Fatigue

1313

Causes of foodborne diseaseCauses of foodborne disease

1414

What Are the What Are the Most CommonMost Common Causes of Causes of foodborne Illnessfoodborne Illness

Those caused by the bacteriaThose caused by the bacteriabull CampylobacterCampylobacterbull SalmonellaSalmonellabull E coli O157H7E coli O157H7

Those caused by a group of virusesThose caused by a group of virusesbull Norwalk and Norwalk-like viruses Norwalk and Norwalk-like viruses

1515

Infectious Non-infectiousInfectious Non-infectious

Bacterial Virus protozoaeBacterial Virus protozoae

Biological Biological NonbiologicalNonbiological

Causes of foodborne diseaseCauses of foodborne disease

1616

Infectious causes of food poisoningInfectious causes of food poisoning

BacteriaBacteria Salmonella species Campylobacter jejuni Staphylococcus aureus Clostridium perfringens Clostridium botulinum Bacillus and other sporing

bacilli Shigella species Ecoli Yersinia enterocolitica Vibrio parahaemolyticus Aeromonas hydrophilia Streptococcus species

Group C E and G The other eg Listeria

monocytogens

Virusesa- Hepatitis Ab- Hepatitis Ec- Smal lrounded structured viruses(SRSV)eg

Norovirus CalicivirusesAstrovirusesRotaviruses

Protozoae Protozoae 1- Giardiasis2- Amoebiasis3 Cryptosporiosis4- Isospora5- Balantidum6- Blastocytosis

hominis7- Microsporidia8- Toxoplasmosis

()

1717

Causes Of foodborneCauses Of foodborne

VirusesVirusesUnlike bacteria viruses do not multiply in FoodsAcquired by

a- Primary contamination From shell Fish From Oysters From Mussels From Vegetables eg Hepatitis A From Vegetables irrigated by untreated water

b- Secondary contamination From Food handlers eg Hepatitis A

1818

Non infective causes of food poisoning

Physical Physical contaminationcontamination- - objects falling in objects falling in to food ndash metal to food ndash metal glass packaging glass packaging materials etcmaterials etc

Chemical Chemical contaminationcontamination- - Bleach cleaning Bleach cleaning chemicals chemicals getting in to food getting in to food heavy metalsheavy metals

Natural Natural contaminationcontamination Poisonous plants Poisonous plants and berries and berries undercooked red undercooked red kidney beanskidney beans

Non biological Biological

1919

Causes of foodborne Diseases (ContinuedCauses of foodborne Diseases (Continued

Biological FromBiological Froma- Mushroomsa- Mushrooms

b- Harmful algal speciesb- Harmful algal species

c- Fish c- Fish egeg Ciguatera Fish poisoningCiguatera Fish poisoning Scombroid Fish poisoning associated with Scombroid Fish poisoning associated with

raised Histamine levelsraised Histamine levels Paralytic shell Fish poisoningParalytic shell Fish poisoning

2020

2121

bull 1- Bovine tuberculosis (milk)bull 2- Brucellosis (milk)bull 3- Toxoplasmosis (meat)bull 4- Listerosis (milk products)bull 5- Mad cow diseases virus etc

Some Diseases Which Are Transmitted By Some Diseases Which Are Transmitted By Food But Not Considered As Food Food But Not Considered As Food PoisoningPoisoning

2222

Exotoxins bull Produced inside bacteria and secreted ndash Enterotoxin Neurotoxin Cardiotoxin

bull Superantigen Type I1048774intense immune response1048774cytokines1048774fever nausea vomitting shock (Staph aureus)

bull Membrane disrupting toxin Type II1048774 lysis of cells by disrupting membrane

bull A-B toxins Type III has two parts ndash A is active enzyme toxin that inhibits protein

synthesis and kills cell ndash B binds to surface so toxin is transported across plasma membrane (Clostridium

2323

Selected Clinical and Epidemiologic Characteristics of Typical Illness Caused By Common foodbornee Pathogens

Pathogen Typical Incubation Period

Duration Typical Clinical Presentation

Assorted Foods

Bacterial Salmonella species

1-3 Days 4-7 Days Gastroenteritis Undercooked eggs or poultry produce

Campylobacter jejuni

2-5 Days 2-10 Days

Gastroenteritis Undercooked poultry unpasteurized

dairy products E coli Enterotoxigenic

1-3 Days 3-7 Days Gastroenteritis Many foods

Shigella species 1-2 Days 4-7 Days Gastroenteritis Produce egg salad

2424

Listeria monocytogenes

2-6 weeks Variable Gastroenteritis meningitis abortion

Deli meat hotdogs unpasteurized dairy products

Bacillus cereus 1-6 hour lt24 hour Vomiting Gastroenteritis

Fried rice meats

Clostridium botulinum

12-72 hour Days-months Blurred vision paralysis

Home-canned foods fermented fish

Staphylococcus aureus

1-6 hour 1-2 Days Gastroenteritis particularly nausea

Meats potato amp pork unpasteurized dairy products

Yersinia enterocolitica

1-2 Days 1-3 weeks Gastroenteritis appendicitis-like syndrome

Undercooked pork unpasteurized dairy products

2525

ViralViral Typical incubation period

Duration Typical clinical presentation

Assorted foods

Norovirus 1-2 Days 12-60 Hr Gastroenteritis

Under

cooked shellfish

Hepatitis A virus

15-50 Days

Weeks-months

Hepatitis Produce undercooked shellfish

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

77

SporeSpore

A A resting resistant phaseresting resistant phase of some bacteria (including of some bacteria (including

Clostridium Perfringens and Botulinum and Bacillus Cereus) Clostridium Perfringens and Botulinum and Bacillus Cereus)

The bacterium produces a protective coat which helps it to The bacterium produces a protective coat which helps it to

survive high temperatures (up to 120degC) and lack of water survive high temperatures (up to 120degC) and lack of water

When When favourable conditions return the spores split openfavourable conditions return the spores split open and and

releaserelease the bacteriathe bacteria which are then able to grow and multiply which are then able to grow and multiply

Spore forming inside cell

88

What Foods Are Most Likely to be What Foods Are Most Likely to be

ContaminatedContaminated raw meat and poultryraw meat and poultry

raw eggs (even in uncooked brownie cake or raw eggs (even in uncooked brownie cake or cookie dough)cookie dough)

unpasteurized milkunpasteurized milk

raw shellfishraw shellfish

unwashed raw fruits and vegetables unwashed raw fruits and vegetables

unpasteurized fruit juiceunpasteurized fruit juice

99

Sources of microbial contamination of foodSources of microbial contamination of food

Food handlerFood handler bad personal hygiene using same bad personal hygiene using same cutting board for meat amp vegetables knife cutting board for meat amp vegetables knife contaminated by bloodcontaminated by blood

Food processingFood processing equipment packaging personal contamination equipment packaging personal contamination

during processingduring processing

Food storageFood storage time amp temp time amp temp

Fecal contaminationFecal contamination in farms prior to collection in farms prior to collection

1010

Types of bacteriaTypes of bacteria

SpoilageSpoilage Not particularly harmful bacteria Not particularly harmful bacteria which cause food to go offwhich cause food to go off

BeneficialBeneficial ldquoGood Bacteriardquo which are used ldquoGood Bacteriardquo which are used to make yoghurt and cheeseto make yoghurt and cheese

PathogenicPathogenic Illness causing bacteria Illness causing bacteria

1111

Symptoms of Microbiological Symptoms of Microbiological Food PoisoningFood Poisoning

Infections require an incubation period ofgenerally 2 to 3 days Typical symptoms abdominal cramps diarrhea nausea buthellipthere can be harsher long-lasting effects

Intoxications are often immediate(sometimes with 20 minutes) with nauseaabdominal cramps and violent vomitingIllness is usually rather short-lived

1212

Symptoms of Symptoms of food poisoningfood poisoning

NauseaAbdominal pain

VomitingDiarrhea

GastroenteritisFever

Headache Fatigue

1313

Causes of foodborne diseaseCauses of foodborne disease

1414

What Are the What Are the Most CommonMost Common Causes of Causes of foodborne Illnessfoodborne Illness

Those caused by the bacteriaThose caused by the bacteriabull CampylobacterCampylobacterbull SalmonellaSalmonellabull E coli O157H7E coli O157H7

Those caused by a group of virusesThose caused by a group of virusesbull Norwalk and Norwalk-like viruses Norwalk and Norwalk-like viruses

1515

Infectious Non-infectiousInfectious Non-infectious

Bacterial Virus protozoaeBacterial Virus protozoae

Biological Biological NonbiologicalNonbiological

Causes of foodborne diseaseCauses of foodborne disease

1616

Infectious causes of food poisoningInfectious causes of food poisoning

BacteriaBacteria Salmonella species Campylobacter jejuni Staphylococcus aureus Clostridium perfringens Clostridium botulinum Bacillus and other sporing

bacilli Shigella species Ecoli Yersinia enterocolitica Vibrio parahaemolyticus Aeromonas hydrophilia Streptococcus species

Group C E and G The other eg Listeria

monocytogens

Virusesa- Hepatitis Ab- Hepatitis Ec- Smal lrounded structured viruses(SRSV)eg

Norovirus CalicivirusesAstrovirusesRotaviruses

Protozoae Protozoae 1- Giardiasis2- Amoebiasis3 Cryptosporiosis4- Isospora5- Balantidum6- Blastocytosis

hominis7- Microsporidia8- Toxoplasmosis

()

1717

Causes Of foodborneCauses Of foodborne

VirusesVirusesUnlike bacteria viruses do not multiply in FoodsAcquired by

a- Primary contamination From shell Fish From Oysters From Mussels From Vegetables eg Hepatitis A From Vegetables irrigated by untreated water

b- Secondary contamination From Food handlers eg Hepatitis A

1818

Non infective causes of food poisoning

Physical Physical contaminationcontamination- - objects falling in objects falling in to food ndash metal to food ndash metal glass packaging glass packaging materials etcmaterials etc

Chemical Chemical contaminationcontamination- - Bleach cleaning Bleach cleaning chemicals chemicals getting in to food getting in to food heavy metalsheavy metals

Natural Natural contaminationcontamination Poisonous plants Poisonous plants and berries and berries undercooked red undercooked red kidney beanskidney beans

Non biological Biological

1919

Causes of foodborne Diseases (ContinuedCauses of foodborne Diseases (Continued

Biological FromBiological Froma- Mushroomsa- Mushrooms

b- Harmful algal speciesb- Harmful algal species

c- Fish c- Fish egeg Ciguatera Fish poisoningCiguatera Fish poisoning Scombroid Fish poisoning associated with Scombroid Fish poisoning associated with

raised Histamine levelsraised Histamine levels Paralytic shell Fish poisoningParalytic shell Fish poisoning

2020

2121

bull 1- Bovine tuberculosis (milk)bull 2- Brucellosis (milk)bull 3- Toxoplasmosis (meat)bull 4- Listerosis (milk products)bull 5- Mad cow diseases virus etc

Some Diseases Which Are Transmitted By Some Diseases Which Are Transmitted By Food But Not Considered As Food Food But Not Considered As Food PoisoningPoisoning

2222

Exotoxins bull Produced inside bacteria and secreted ndash Enterotoxin Neurotoxin Cardiotoxin

bull Superantigen Type I1048774intense immune response1048774cytokines1048774fever nausea vomitting shock (Staph aureus)

bull Membrane disrupting toxin Type II1048774 lysis of cells by disrupting membrane

bull A-B toxins Type III has two parts ndash A is active enzyme toxin that inhibits protein

synthesis and kills cell ndash B binds to surface so toxin is transported across plasma membrane (Clostridium

2323

Selected Clinical and Epidemiologic Characteristics of Typical Illness Caused By Common foodbornee Pathogens

Pathogen Typical Incubation Period

Duration Typical Clinical Presentation

Assorted Foods

Bacterial Salmonella species

1-3 Days 4-7 Days Gastroenteritis Undercooked eggs or poultry produce

Campylobacter jejuni

2-5 Days 2-10 Days

Gastroenteritis Undercooked poultry unpasteurized

dairy products E coli Enterotoxigenic

1-3 Days 3-7 Days Gastroenteritis Many foods

Shigella species 1-2 Days 4-7 Days Gastroenteritis Produce egg salad

2424

Listeria monocytogenes

2-6 weeks Variable Gastroenteritis meningitis abortion

Deli meat hotdogs unpasteurized dairy products

Bacillus cereus 1-6 hour lt24 hour Vomiting Gastroenteritis

Fried rice meats

Clostridium botulinum

12-72 hour Days-months Blurred vision paralysis

Home-canned foods fermented fish

Staphylococcus aureus

1-6 hour 1-2 Days Gastroenteritis particularly nausea

Meats potato amp pork unpasteurized dairy products

Yersinia enterocolitica

1-2 Days 1-3 weeks Gastroenteritis appendicitis-like syndrome

Undercooked pork unpasteurized dairy products

2525

ViralViral Typical incubation period

Duration Typical clinical presentation

Assorted foods

Norovirus 1-2 Days 12-60 Hr Gastroenteritis

Under

cooked shellfish

Hepatitis A virus

15-50 Days

Weeks-months

Hepatitis Produce undercooked shellfish

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

88

What Foods Are Most Likely to be What Foods Are Most Likely to be

ContaminatedContaminated raw meat and poultryraw meat and poultry

raw eggs (even in uncooked brownie cake or raw eggs (even in uncooked brownie cake or cookie dough)cookie dough)

unpasteurized milkunpasteurized milk

raw shellfishraw shellfish

unwashed raw fruits and vegetables unwashed raw fruits and vegetables

unpasteurized fruit juiceunpasteurized fruit juice

99

Sources of microbial contamination of foodSources of microbial contamination of food

Food handlerFood handler bad personal hygiene using same bad personal hygiene using same cutting board for meat amp vegetables knife cutting board for meat amp vegetables knife contaminated by bloodcontaminated by blood

Food processingFood processing equipment packaging personal contamination equipment packaging personal contamination

during processingduring processing

Food storageFood storage time amp temp time amp temp

Fecal contaminationFecal contamination in farms prior to collection in farms prior to collection

1010

Types of bacteriaTypes of bacteria

SpoilageSpoilage Not particularly harmful bacteria Not particularly harmful bacteria which cause food to go offwhich cause food to go off

BeneficialBeneficial ldquoGood Bacteriardquo which are used ldquoGood Bacteriardquo which are used to make yoghurt and cheeseto make yoghurt and cheese

PathogenicPathogenic Illness causing bacteria Illness causing bacteria

1111

Symptoms of Microbiological Symptoms of Microbiological Food PoisoningFood Poisoning

Infections require an incubation period ofgenerally 2 to 3 days Typical symptoms abdominal cramps diarrhea nausea buthellipthere can be harsher long-lasting effects

Intoxications are often immediate(sometimes with 20 minutes) with nauseaabdominal cramps and violent vomitingIllness is usually rather short-lived

1212

Symptoms of Symptoms of food poisoningfood poisoning

NauseaAbdominal pain

VomitingDiarrhea

GastroenteritisFever

Headache Fatigue

1313

Causes of foodborne diseaseCauses of foodborne disease

1414

What Are the What Are the Most CommonMost Common Causes of Causes of foodborne Illnessfoodborne Illness

Those caused by the bacteriaThose caused by the bacteriabull CampylobacterCampylobacterbull SalmonellaSalmonellabull E coli O157H7E coli O157H7

Those caused by a group of virusesThose caused by a group of virusesbull Norwalk and Norwalk-like viruses Norwalk and Norwalk-like viruses

1515

Infectious Non-infectiousInfectious Non-infectious

Bacterial Virus protozoaeBacterial Virus protozoae

Biological Biological NonbiologicalNonbiological

Causes of foodborne diseaseCauses of foodborne disease

1616

Infectious causes of food poisoningInfectious causes of food poisoning

BacteriaBacteria Salmonella species Campylobacter jejuni Staphylococcus aureus Clostridium perfringens Clostridium botulinum Bacillus and other sporing

bacilli Shigella species Ecoli Yersinia enterocolitica Vibrio parahaemolyticus Aeromonas hydrophilia Streptococcus species

Group C E and G The other eg Listeria

monocytogens

Virusesa- Hepatitis Ab- Hepatitis Ec- Smal lrounded structured viruses(SRSV)eg

Norovirus CalicivirusesAstrovirusesRotaviruses

Protozoae Protozoae 1- Giardiasis2- Amoebiasis3 Cryptosporiosis4- Isospora5- Balantidum6- Blastocytosis

hominis7- Microsporidia8- Toxoplasmosis

()

1717

Causes Of foodborneCauses Of foodborne

VirusesVirusesUnlike bacteria viruses do not multiply in FoodsAcquired by

a- Primary contamination From shell Fish From Oysters From Mussels From Vegetables eg Hepatitis A From Vegetables irrigated by untreated water

b- Secondary contamination From Food handlers eg Hepatitis A

1818

Non infective causes of food poisoning

Physical Physical contaminationcontamination- - objects falling in objects falling in to food ndash metal to food ndash metal glass packaging glass packaging materials etcmaterials etc

Chemical Chemical contaminationcontamination- - Bleach cleaning Bleach cleaning chemicals chemicals getting in to food getting in to food heavy metalsheavy metals

Natural Natural contaminationcontamination Poisonous plants Poisonous plants and berries and berries undercooked red undercooked red kidney beanskidney beans

Non biological Biological

1919

Causes of foodborne Diseases (ContinuedCauses of foodborne Diseases (Continued

Biological FromBiological Froma- Mushroomsa- Mushrooms

b- Harmful algal speciesb- Harmful algal species

c- Fish c- Fish egeg Ciguatera Fish poisoningCiguatera Fish poisoning Scombroid Fish poisoning associated with Scombroid Fish poisoning associated with

raised Histamine levelsraised Histamine levels Paralytic shell Fish poisoningParalytic shell Fish poisoning

2020

2121

bull 1- Bovine tuberculosis (milk)bull 2- Brucellosis (milk)bull 3- Toxoplasmosis (meat)bull 4- Listerosis (milk products)bull 5- Mad cow diseases virus etc

Some Diseases Which Are Transmitted By Some Diseases Which Are Transmitted By Food But Not Considered As Food Food But Not Considered As Food PoisoningPoisoning

2222

Exotoxins bull Produced inside bacteria and secreted ndash Enterotoxin Neurotoxin Cardiotoxin

bull Superantigen Type I1048774intense immune response1048774cytokines1048774fever nausea vomitting shock (Staph aureus)

bull Membrane disrupting toxin Type II1048774 lysis of cells by disrupting membrane

bull A-B toxins Type III has two parts ndash A is active enzyme toxin that inhibits protein

synthesis and kills cell ndash B binds to surface so toxin is transported across plasma membrane (Clostridium

2323

Selected Clinical and Epidemiologic Characteristics of Typical Illness Caused By Common foodbornee Pathogens

Pathogen Typical Incubation Period

Duration Typical Clinical Presentation

Assorted Foods

Bacterial Salmonella species

1-3 Days 4-7 Days Gastroenteritis Undercooked eggs or poultry produce

Campylobacter jejuni

2-5 Days 2-10 Days

Gastroenteritis Undercooked poultry unpasteurized

dairy products E coli Enterotoxigenic

1-3 Days 3-7 Days Gastroenteritis Many foods

Shigella species 1-2 Days 4-7 Days Gastroenteritis Produce egg salad

2424

Listeria monocytogenes

2-6 weeks Variable Gastroenteritis meningitis abortion

Deli meat hotdogs unpasteurized dairy products

Bacillus cereus 1-6 hour lt24 hour Vomiting Gastroenteritis

Fried rice meats

Clostridium botulinum

12-72 hour Days-months Blurred vision paralysis

Home-canned foods fermented fish

Staphylococcus aureus

1-6 hour 1-2 Days Gastroenteritis particularly nausea

Meats potato amp pork unpasteurized dairy products

Yersinia enterocolitica

1-2 Days 1-3 weeks Gastroenteritis appendicitis-like syndrome

Undercooked pork unpasteurized dairy products

2525

ViralViral Typical incubation period

Duration Typical clinical presentation

Assorted foods

Norovirus 1-2 Days 12-60 Hr Gastroenteritis

Under

cooked shellfish

Hepatitis A virus

15-50 Days

Weeks-months

Hepatitis Produce undercooked shellfish

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

99

Sources of microbial contamination of foodSources of microbial contamination of food

Food handlerFood handler bad personal hygiene using same bad personal hygiene using same cutting board for meat amp vegetables knife cutting board for meat amp vegetables knife contaminated by bloodcontaminated by blood

Food processingFood processing equipment packaging personal contamination equipment packaging personal contamination

during processingduring processing

Food storageFood storage time amp temp time amp temp

Fecal contaminationFecal contamination in farms prior to collection in farms prior to collection

1010

Types of bacteriaTypes of bacteria

SpoilageSpoilage Not particularly harmful bacteria Not particularly harmful bacteria which cause food to go offwhich cause food to go off

BeneficialBeneficial ldquoGood Bacteriardquo which are used ldquoGood Bacteriardquo which are used to make yoghurt and cheeseto make yoghurt and cheese

PathogenicPathogenic Illness causing bacteria Illness causing bacteria

1111

Symptoms of Microbiological Symptoms of Microbiological Food PoisoningFood Poisoning

Infections require an incubation period ofgenerally 2 to 3 days Typical symptoms abdominal cramps diarrhea nausea buthellipthere can be harsher long-lasting effects

Intoxications are often immediate(sometimes with 20 minutes) with nauseaabdominal cramps and violent vomitingIllness is usually rather short-lived

1212

Symptoms of Symptoms of food poisoningfood poisoning

NauseaAbdominal pain

VomitingDiarrhea

GastroenteritisFever

Headache Fatigue

1313

Causes of foodborne diseaseCauses of foodborne disease

1414

What Are the What Are the Most CommonMost Common Causes of Causes of foodborne Illnessfoodborne Illness

Those caused by the bacteriaThose caused by the bacteriabull CampylobacterCampylobacterbull SalmonellaSalmonellabull E coli O157H7E coli O157H7

Those caused by a group of virusesThose caused by a group of virusesbull Norwalk and Norwalk-like viruses Norwalk and Norwalk-like viruses

1515

Infectious Non-infectiousInfectious Non-infectious

Bacterial Virus protozoaeBacterial Virus protozoae

Biological Biological NonbiologicalNonbiological

Causes of foodborne diseaseCauses of foodborne disease

1616

Infectious causes of food poisoningInfectious causes of food poisoning

BacteriaBacteria Salmonella species Campylobacter jejuni Staphylococcus aureus Clostridium perfringens Clostridium botulinum Bacillus and other sporing

bacilli Shigella species Ecoli Yersinia enterocolitica Vibrio parahaemolyticus Aeromonas hydrophilia Streptococcus species

Group C E and G The other eg Listeria

monocytogens

Virusesa- Hepatitis Ab- Hepatitis Ec- Smal lrounded structured viruses(SRSV)eg

Norovirus CalicivirusesAstrovirusesRotaviruses

Protozoae Protozoae 1- Giardiasis2- Amoebiasis3 Cryptosporiosis4- Isospora5- Balantidum6- Blastocytosis

hominis7- Microsporidia8- Toxoplasmosis

()

1717

Causes Of foodborneCauses Of foodborne

VirusesVirusesUnlike bacteria viruses do not multiply in FoodsAcquired by

a- Primary contamination From shell Fish From Oysters From Mussels From Vegetables eg Hepatitis A From Vegetables irrigated by untreated water

b- Secondary contamination From Food handlers eg Hepatitis A

1818

Non infective causes of food poisoning

Physical Physical contaminationcontamination- - objects falling in objects falling in to food ndash metal to food ndash metal glass packaging glass packaging materials etcmaterials etc

Chemical Chemical contaminationcontamination- - Bleach cleaning Bleach cleaning chemicals chemicals getting in to food getting in to food heavy metalsheavy metals

Natural Natural contaminationcontamination Poisonous plants Poisonous plants and berries and berries undercooked red undercooked red kidney beanskidney beans

Non biological Biological

1919

Causes of foodborne Diseases (ContinuedCauses of foodborne Diseases (Continued

Biological FromBiological Froma- Mushroomsa- Mushrooms

b- Harmful algal speciesb- Harmful algal species

c- Fish c- Fish egeg Ciguatera Fish poisoningCiguatera Fish poisoning Scombroid Fish poisoning associated with Scombroid Fish poisoning associated with

raised Histamine levelsraised Histamine levels Paralytic shell Fish poisoningParalytic shell Fish poisoning

2020

2121

bull 1- Bovine tuberculosis (milk)bull 2- Brucellosis (milk)bull 3- Toxoplasmosis (meat)bull 4- Listerosis (milk products)bull 5- Mad cow diseases virus etc

Some Diseases Which Are Transmitted By Some Diseases Which Are Transmitted By Food But Not Considered As Food Food But Not Considered As Food PoisoningPoisoning

2222

Exotoxins bull Produced inside bacteria and secreted ndash Enterotoxin Neurotoxin Cardiotoxin

bull Superantigen Type I1048774intense immune response1048774cytokines1048774fever nausea vomitting shock (Staph aureus)

bull Membrane disrupting toxin Type II1048774 lysis of cells by disrupting membrane

bull A-B toxins Type III has two parts ndash A is active enzyme toxin that inhibits protein

synthesis and kills cell ndash B binds to surface so toxin is transported across plasma membrane (Clostridium

2323

Selected Clinical and Epidemiologic Characteristics of Typical Illness Caused By Common foodbornee Pathogens

Pathogen Typical Incubation Period

Duration Typical Clinical Presentation

Assorted Foods

Bacterial Salmonella species

1-3 Days 4-7 Days Gastroenteritis Undercooked eggs or poultry produce

Campylobacter jejuni

2-5 Days 2-10 Days

Gastroenteritis Undercooked poultry unpasteurized

dairy products E coli Enterotoxigenic

1-3 Days 3-7 Days Gastroenteritis Many foods

Shigella species 1-2 Days 4-7 Days Gastroenteritis Produce egg salad

2424

Listeria monocytogenes

2-6 weeks Variable Gastroenteritis meningitis abortion

Deli meat hotdogs unpasteurized dairy products

Bacillus cereus 1-6 hour lt24 hour Vomiting Gastroenteritis

Fried rice meats

Clostridium botulinum

12-72 hour Days-months Blurred vision paralysis

Home-canned foods fermented fish

Staphylococcus aureus

1-6 hour 1-2 Days Gastroenteritis particularly nausea

Meats potato amp pork unpasteurized dairy products

Yersinia enterocolitica

1-2 Days 1-3 weeks Gastroenteritis appendicitis-like syndrome

Undercooked pork unpasteurized dairy products

2525

ViralViral Typical incubation period

Duration Typical clinical presentation

Assorted foods

Norovirus 1-2 Days 12-60 Hr Gastroenteritis

Under

cooked shellfish

Hepatitis A virus

15-50 Days

Weeks-months

Hepatitis Produce undercooked shellfish

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

1010

Types of bacteriaTypes of bacteria

SpoilageSpoilage Not particularly harmful bacteria Not particularly harmful bacteria which cause food to go offwhich cause food to go off

BeneficialBeneficial ldquoGood Bacteriardquo which are used ldquoGood Bacteriardquo which are used to make yoghurt and cheeseto make yoghurt and cheese

PathogenicPathogenic Illness causing bacteria Illness causing bacteria

1111

Symptoms of Microbiological Symptoms of Microbiological Food PoisoningFood Poisoning

Infections require an incubation period ofgenerally 2 to 3 days Typical symptoms abdominal cramps diarrhea nausea buthellipthere can be harsher long-lasting effects

Intoxications are often immediate(sometimes with 20 minutes) with nauseaabdominal cramps and violent vomitingIllness is usually rather short-lived

1212

Symptoms of Symptoms of food poisoningfood poisoning

NauseaAbdominal pain

VomitingDiarrhea

GastroenteritisFever

Headache Fatigue

1313

Causes of foodborne diseaseCauses of foodborne disease

1414

What Are the What Are the Most CommonMost Common Causes of Causes of foodborne Illnessfoodborne Illness

Those caused by the bacteriaThose caused by the bacteriabull CampylobacterCampylobacterbull SalmonellaSalmonellabull E coli O157H7E coli O157H7

Those caused by a group of virusesThose caused by a group of virusesbull Norwalk and Norwalk-like viruses Norwalk and Norwalk-like viruses

1515

Infectious Non-infectiousInfectious Non-infectious

Bacterial Virus protozoaeBacterial Virus protozoae

Biological Biological NonbiologicalNonbiological

Causes of foodborne diseaseCauses of foodborne disease

1616

Infectious causes of food poisoningInfectious causes of food poisoning

BacteriaBacteria Salmonella species Campylobacter jejuni Staphylococcus aureus Clostridium perfringens Clostridium botulinum Bacillus and other sporing

bacilli Shigella species Ecoli Yersinia enterocolitica Vibrio parahaemolyticus Aeromonas hydrophilia Streptococcus species

Group C E and G The other eg Listeria

monocytogens

Virusesa- Hepatitis Ab- Hepatitis Ec- Smal lrounded structured viruses(SRSV)eg

Norovirus CalicivirusesAstrovirusesRotaviruses

Protozoae Protozoae 1- Giardiasis2- Amoebiasis3 Cryptosporiosis4- Isospora5- Balantidum6- Blastocytosis

hominis7- Microsporidia8- Toxoplasmosis

()

1717

Causes Of foodborneCauses Of foodborne

VirusesVirusesUnlike bacteria viruses do not multiply in FoodsAcquired by

a- Primary contamination From shell Fish From Oysters From Mussels From Vegetables eg Hepatitis A From Vegetables irrigated by untreated water

b- Secondary contamination From Food handlers eg Hepatitis A

1818

Non infective causes of food poisoning

Physical Physical contaminationcontamination- - objects falling in objects falling in to food ndash metal to food ndash metal glass packaging glass packaging materials etcmaterials etc

Chemical Chemical contaminationcontamination- - Bleach cleaning Bleach cleaning chemicals chemicals getting in to food getting in to food heavy metalsheavy metals

Natural Natural contaminationcontamination Poisonous plants Poisonous plants and berries and berries undercooked red undercooked red kidney beanskidney beans

Non biological Biological

1919

Causes of foodborne Diseases (ContinuedCauses of foodborne Diseases (Continued

Biological FromBiological Froma- Mushroomsa- Mushrooms

b- Harmful algal speciesb- Harmful algal species

c- Fish c- Fish egeg Ciguatera Fish poisoningCiguatera Fish poisoning Scombroid Fish poisoning associated with Scombroid Fish poisoning associated with

raised Histamine levelsraised Histamine levels Paralytic shell Fish poisoningParalytic shell Fish poisoning

2020

2121

bull 1- Bovine tuberculosis (milk)bull 2- Brucellosis (milk)bull 3- Toxoplasmosis (meat)bull 4- Listerosis (milk products)bull 5- Mad cow diseases virus etc

Some Diseases Which Are Transmitted By Some Diseases Which Are Transmitted By Food But Not Considered As Food Food But Not Considered As Food PoisoningPoisoning

2222

Exotoxins bull Produced inside bacteria and secreted ndash Enterotoxin Neurotoxin Cardiotoxin

bull Superantigen Type I1048774intense immune response1048774cytokines1048774fever nausea vomitting shock (Staph aureus)

bull Membrane disrupting toxin Type II1048774 lysis of cells by disrupting membrane

bull A-B toxins Type III has two parts ndash A is active enzyme toxin that inhibits protein

synthesis and kills cell ndash B binds to surface so toxin is transported across plasma membrane (Clostridium

2323

Selected Clinical and Epidemiologic Characteristics of Typical Illness Caused By Common foodbornee Pathogens

Pathogen Typical Incubation Period

Duration Typical Clinical Presentation

Assorted Foods

Bacterial Salmonella species

1-3 Days 4-7 Days Gastroenteritis Undercooked eggs or poultry produce

Campylobacter jejuni

2-5 Days 2-10 Days

Gastroenteritis Undercooked poultry unpasteurized

dairy products E coli Enterotoxigenic

1-3 Days 3-7 Days Gastroenteritis Many foods

Shigella species 1-2 Days 4-7 Days Gastroenteritis Produce egg salad

2424

Listeria monocytogenes

2-6 weeks Variable Gastroenteritis meningitis abortion

Deli meat hotdogs unpasteurized dairy products

Bacillus cereus 1-6 hour lt24 hour Vomiting Gastroenteritis

Fried rice meats

Clostridium botulinum

12-72 hour Days-months Blurred vision paralysis

Home-canned foods fermented fish

Staphylococcus aureus

1-6 hour 1-2 Days Gastroenteritis particularly nausea

Meats potato amp pork unpasteurized dairy products

Yersinia enterocolitica

1-2 Days 1-3 weeks Gastroenteritis appendicitis-like syndrome

Undercooked pork unpasteurized dairy products

2525

ViralViral Typical incubation period

Duration Typical clinical presentation

Assorted foods

Norovirus 1-2 Days 12-60 Hr Gastroenteritis

Under

cooked shellfish

Hepatitis A virus

15-50 Days

Weeks-months

Hepatitis Produce undercooked shellfish

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

1111

Symptoms of Microbiological Symptoms of Microbiological Food PoisoningFood Poisoning

Infections require an incubation period ofgenerally 2 to 3 days Typical symptoms abdominal cramps diarrhea nausea buthellipthere can be harsher long-lasting effects

Intoxications are often immediate(sometimes with 20 minutes) with nauseaabdominal cramps and violent vomitingIllness is usually rather short-lived

1212

Symptoms of Symptoms of food poisoningfood poisoning

NauseaAbdominal pain

VomitingDiarrhea

GastroenteritisFever

Headache Fatigue

1313

Causes of foodborne diseaseCauses of foodborne disease

1414

What Are the What Are the Most CommonMost Common Causes of Causes of foodborne Illnessfoodborne Illness

Those caused by the bacteriaThose caused by the bacteriabull CampylobacterCampylobacterbull SalmonellaSalmonellabull E coli O157H7E coli O157H7

Those caused by a group of virusesThose caused by a group of virusesbull Norwalk and Norwalk-like viruses Norwalk and Norwalk-like viruses

1515

Infectious Non-infectiousInfectious Non-infectious

Bacterial Virus protozoaeBacterial Virus protozoae

Biological Biological NonbiologicalNonbiological

Causes of foodborne diseaseCauses of foodborne disease

1616

Infectious causes of food poisoningInfectious causes of food poisoning

BacteriaBacteria Salmonella species Campylobacter jejuni Staphylococcus aureus Clostridium perfringens Clostridium botulinum Bacillus and other sporing

bacilli Shigella species Ecoli Yersinia enterocolitica Vibrio parahaemolyticus Aeromonas hydrophilia Streptococcus species

Group C E and G The other eg Listeria

monocytogens

Virusesa- Hepatitis Ab- Hepatitis Ec- Smal lrounded structured viruses(SRSV)eg

Norovirus CalicivirusesAstrovirusesRotaviruses

Protozoae Protozoae 1- Giardiasis2- Amoebiasis3 Cryptosporiosis4- Isospora5- Balantidum6- Blastocytosis

hominis7- Microsporidia8- Toxoplasmosis

()

1717

Causes Of foodborneCauses Of foodborne

VirusesVirusesUnlike bacteria viruses do not multiply in FoodsAcquired by

a- Primary contamination From shell Fish From Oysters From Mussels From Vegetables eg Hepatitis A From Vegetables irrigated by untreated water

b- Secondary contamination From Food handlers eg Hepatitis A

1818

Non infective causes of food poisoning

Physical Physical contaminationcontamination- - objects falling in objects falling in to food ndash metal to food ndash metal glass packaging glass packaging materials etcmaterials etc

Chemical Chemical contaminationcontamination- - Bleach cleaning Bleach cleaning chemicals chemicals getting in to food getting in to food heavy metalsheavy metals

Natural Natural contaminationcontamination Poisonous plants Poisonous plants and berries and berries undercooked red undercooked red kidney beanskidney beans

Non biological Biological

1919

Causes of foodborne Diseases (ContinuedCauses of foodborne Diseases (Continued

Biological FromBiological Froma- Mushroomsa- Mushrooms

b- Harmful algal speciesb- Harmful algal species

c- Fish c- Fish egeg Ciguatera Fish poisoningCiguatera Fish poisoning Scombroid Fish poisoning associated with Scombroid Fish poisoning associated with

raised Histamine levelsraised Histamine levels Paralytic shell Fish poisoningParalytic shell Fish poisoning

2020

2121

bull 1- Bovine tuberculosis (milk)bull 2- Brucellosis (milk)bull 3- Toxoplasmosis (meat)bull 4- Listerosis (milk products)bull 5- Mad cow diseases virus etc

Some Diseases Which Are Transmitted By Some Diseases Which Are Transmitted By Food But Not Considered As Food Food But Not Considered As Food PoisoningPoisoning

2222

Exotoxins bull Produced inside bacteria and secreted ndash Enterotoxin Neurotoxin Cardiotoxin

bull Superantigen Type I1048774intense immune response1048774cytokines1048774fever nausea vomitting shock (Staph aureus)

bull Membrane disrupting toxin Type II1048774 lysis of cells by disrupting membrane

bull A-B toxins Type III has two parts ndash A is active enzyme toxin that inhibits protein

synthesis and kills cell ndash B binds to surface so toxin is transported across plasma membrane (Clostridium

2323

Selected Clinical and Epidemiologic Characteristics of Typical Illness Caused By Common foodbornee Pathogens

Pathogen Typical Incubation Period

Duration Typical Clinical Presentation

Assorted Foods

Bacterial Salmonella species

1-3 Days 4-7 Days Gastroenteritis Undercooked eggs or poultry produce

Campylobacter jejuni

2-5 Days 2-10 Days

Gastroenteritis Undercooked poultry unpasteurized

dairy products E coli Enterotoxigenic

1-3 Days 3-7 Days Gastroenteritis Many foods

Shigella species 1-2 Days 4-7 Days Gastroenteritis Produce egg salad

2424

Listeria monocytogenes

2-6 weeks Variable Gastroenteritis meningitis abortion

Deli meat hotdogs unpasteurized dairy products

Bacillus cereus 1-6 hour lt24 hour Vomiting Gastroenteritis

Fried rice meats

Clostridium botulinum

12-72 hour Days-months Blurred vision paralysis

Home-canned foods fermented fish

Staphylococcus aureus

1-6 hour 1-2 Days Gastroenteritis particularly nausea

Meats potato amp pork unpasteurized dairy products

Yersinia enterocolitica

1-2 Days 1-3 weeks Gastroenteritis appendicitis-like syndrome

Undercooked pork unpasteurized dairy products

2525

ViralViral Typical incubation period

Duration Typical clinical presentation

Assorted foods

Norovirus 1-2 Days 12-60 Hr Gastroenteritis

Under

cooked shellfish

Hepatitis A virus

15-50 Days

Weeks-months

Hepatitis Produce undercooked shellfish

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

1212

Symptoms of Symptoms of food poisoningfood poisoning

NauseaAbdominal pain

VomitingDiarrhea

GastroenteritisFever

Headache Fatigue

1313

Causes of foodborne diseaseCauses of foodborne disease

1414

What Are the What Are the Most CommonMost Common Causes of Causes of foodborne Illnessfoodborne Illness

Those caused by the bacteriaThose caused by the bacteriabull CampylobacterCampylobacterbull SalmonellaSalmonellabull E coli O157H7E coli O157H7

Those caused by a group of virusesThose caused by a group of virusesbull Norwalk and Norwalk-like viruses Norwalk and Norwalk-like viruses

1515

Infectious Non-infectiousInfectious Non-infectious

Bacterial Virus protozoaeBacterial Virus protozoae

Biological Biological NonbiologicalNonbiological

Causes of foodborne diseaseCauses of foodborne disease

1616

Infectious causes of food poisoningInfectious causes of food poisoning

BacteriaBacteria Salmonella species Campylobacter jejuni Staphylococcus aureus Clostridium perfringens Clostridium botulinum Bacillus and other sporing

bacilli Shigella species Ecoli Yersinia enterocolitica Vibrio parahaemolyticus Aeromonas hydrophilia Streptococcus species

Group C E and G The other eg Listeria

monocytogens

Virusesa- Hepatitis Ab- Hepatitis Ec- Smal lrounded structured viruses(SRSV)eg

Norovirus CalicivirusesAstrovirusesRotaviruses

Protozoae Protozoae 1- Giardiasis2- Amoebiasis3 Cryptosporiosis4- Isospora5- Balantidum6- Blastocytosis

hominis7- Microsporidia8- Toxoplasmosis

()

1717

Causes Of foodborneCauses Of foodborne

VirusesVirusesUnlike bacteria viruses do not multiply in FoodsAcquired by

a- Primary contamination From shell Fish From Oysters From Mussels From Vegetables eg Hepatitis A From Vegetables irrigated by untreated water

b- Secondary contamination From Food handlers eg Hepatitis A

1818

Non infective causes of food poisoning

Physical Physical contaminationcontamination- - objects falling in objects falling in to food ndash metal to food ndash metal glass packaging glass packaging materials etcmaterials etc

Chemical Chemical contaminationcontamination- - Bleach cleaning Bleach cleaning chemicals chemicals getting in to food getting in to food heavy metalsheavy metals

Natural Natural contaminationcontamination Poisonous plants Poisonous plants and berries and berries undercooked red undercooked red kidney beanskidney beans

Non biological Biological

1919

Causes of foodborne Diseases (ContinuedCauses of foodborne Diseases (Continued

Biological FromBiological Froma- Mushroomsa- Mushrooms

b- Harmful algal speciesb- Harmful algal species

c- Fish c- Fish egeg Ciguatera Fish poisoningCiguatera Fish poisoning Scombroid Fish poisoning associated with Scombroid Fish poisoning associated with

raised Histamine levelsraised Histamine levels Paralytic shell Fish poisoningParalytic shell Fish poisoning

2020

2121

bull 1- Bovine tuberculosis (milk)bull 2- Brucellosis (milk)bull 3- Toxoplasmosis (meat)bull 4- Listerosis (milk products)bull 5- Mad cow diseases virus etc

Some Diseases Which Are Transmitted By Some Diseases Which Are Transmitted By Food But Not Considered As Food Food But Not Considered As Food PoisoningPoisoning

2222

Exotoxins bull Produced inside bacteria and secreted ndash Enterotoxin Neurotoxin Cardiotoxin

bull Superantigen Type I1048774intense immune response1048774cytokines1048774fever nausea vomitting shock (Staph aureus)

bull Membrane disrupting toxin Type II1048774 lysis of cells by disrupting membrane

bull A-B toxins Type III has two parts ndash A is active enzyme toxin that inhibits protein

synthesis and kills cell ndash B binds to surface so toxin is transported across plasma membrane (Clostridium

2323

Selected Clinical and Epidemiologic Characteristics of Typical Illness Caused By Common foodbornee Pathogens

Pathogen Typical Incubation Period

Duration Typical Clinical Presentation

Assorted Foods

Bacterial Salmonella species

1-3 Days 4-7 Days Gastroenteritis Undercooked eggs or poultry produce

Campylobacter jejuni

2-5 Days 2-10 Days

Gastroenteritis Undercooked poultry unpasteurized

dairy products E coli Enterotoxigenic

1-3 Days 3-7 Days Gastroenteritis Many foods

Shigella species 1-2 Days 4-7 Days Gastroenteritis Produce egg salad

2424

Listeria monocytogenes

2-6 weeks Variable Gastroenteritis meningitis abortion

Deli meat hotdogs unpasteurized dairy products

Bacillus cereus 1-6 hour lt24 hour Vomiting Gastroenteritis

Fried rice meats

Clostridium botulinum

12-72 hour Days-months Blurred vision paralysis

Home-canned foods fermented fish

Staphylococcus aureus

1-6 hour 1-2 Days Gastroenteritis particularly nausea

Meats potato amp pork unpasteurized dairy products

Yersinia enterocolitica

1-2 Days 1-3 weeks Gastroenteritis appendicitis-like syndrome

Undercooked pork unpasteurized dairy products

2525

ViralViral Typical incubation period

Duration Typical clinical presentation

Assorted foods

Norovirus 1-2 Days 12-60 Hr Gastroenteritis

Under

cooked shellfish

Hepatitis A virus

15-50 Days

Weeks-months

Hepatitis Produce undercooked shellfish

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

1313

Causes of foodborne diseaseCauses of foodborne disease

1414

What Are the What Are the Most CommonMost Common Causes of Causes of foodborne Illnessfoodborne Illness

Those caused by the bacteriaThose caused by the bacteriabull CampylobacterCampylobacterbull SalmonellaSalmonellabull E coli O157H7E coli O157H7

Those caused by a group of virusesThose caused by a group of virusesbull Norwalk and Norwalk-like viruses Norwalk and Norwalk-like viruses

1515

Infectious Non-infectiousInfectious Non-infectious

Bacterial Virus protozoaeBacterial Virus protozoae

Biological Biological NonbiologicalNonbiological

Causes of foodborne diseaseCauses of foodborne disease

1616

Infectious causes of food poisoningInfectious causes of food poisoning

BacteriaBacteria Salmonella species Campylobacter jejuni Staphylococcus aureus Clostridium perfringens Clostridium botulinum Bacillus and other sporing

bacilli Shigella species Ecoli Yersinia enterocolitica Vibrio parahaemolyticus Aeromonas hydrophilia Streptococcus species

Group C E and G The other eg Listeria

monocytogens

Virusesa- Hepatitis Ab- Hepatitis Ec- Smal lrounded structured viruses(SRSV)eg

Norovirus CalicivirusesAstrovirusesRotaviruses

Protozoae Protozoae 1- Giardiasis2- Amoebiasis3 Cryptosporiosis4- Isospora5- Balantidum6- Blastocytosis

hominis7- Microsporidia8- Toxoplasmosis

()

1717

Causes Of foodborneCauses Of foodborne

VirusesVirusesUnlike bacteria viruses do not multiply in FoodsAcquired by

a- Primary contamination From shell Fish From Oysters From Mussels From Vegetables eg Hepatitis A From Vegetables irrigated by untreated water

b- Secondary contamination From Food handlers eg Hepatitis A

1818

Non infective causes of food poisoning

Physical Physical contaminationcontamination- - objects falling in objects falling in to food ndash metal to food ndash metal glass packaging glass packaging materials etcmaterials etc

Chemical Chemical contaminationcontamination- - Bleach cleaning Bleach cleaning chemicals chemicals getting in to food getting in to food heavy metalsheavy metals

Natural Natural contaminationcontamination Poisonous plants Poisonous plants and berries and berries undercooked red undercooked red kidney beanskidney beans

Non biological Biological

1919

Causes of foodborne Diseases (ContinuedCauses of foodborne Diseases (Continued

Biological FromBiological Froma- Mushroomsa- Mushrooms

b- Harmful algal speciesb- Harmful algal species

c- Fish c- Fish egeg Ciguatera Fish poisoningCiguatera Fish poisoning Scombroid Fish poisoning associated with Scombroid Fish poisoning associated with

raised Histamine levelsraised Histamine levels Paralytic shell Fish poisoningParalytic shell Fish poisoning

2020

2121

bull 1- Bovine tuberculosis (milk)bull 2- Brucellosis (milk)bull 3- Toxoplasmosis (meat)bull 4- Listerosis (milk products)bull 5- Mad cow diseases virus etc

Some Diseases Which Are Transmitted By Some Diseases Which Are Transmitted By Food But Not Considered As Food Food But Not Considered As Food PoisoningPoisoning

2222

Exotoxins bull Produced inside bacteria and secreted ndash Enterotoxin Neurotoxin Cardiotoxin

bull Superantigen Type I1048774intense immune response1048774cytokines1048774fever nausea vomitting shock (Staph aureus)

bull Membrane disrupting toxin Type II1048774 lysis of cells by disrupting membrane

bull A-B toxins Type III has two parts ndash A is active enzyme toxin that inhibits protein

synthesis and kills cell ndash B binds to surface so toxin is transported across plasma membrane (Clostridium

2323

Selected Clinical and Epidemiologic Characteristics of Typical Illness Caused By Common foodbornee Pathogens

Pathogen Typical Incubation Period

Duration Typical Clinical Presentation

Assorted Foods

Bacterial Salmonella species

1-3 Days 4-7 Days Gastroenteritis Undercooked eggs or poultry produce

Campylobacter jejuni

2-5 Days 2-10 Days

Gastroenteritis Undercooked poultry unpasteurized

dairy products E coli Enterotoxigenic

1-3 Days 3-7 Days Gastroenteritis Many foods

Shigella species 1-2 Days 4-7 Days Gastroenteritis Produce egg salad

2424

Listeria monocytogenes

2-6 weeks Variable Gastroenteritis meningitis abortion

Deli meat hotdogs unpasteurized dairy products

Bacillus cereus 1-6 hour lt24 hour Vomiting Gastroenteritis

Fried rice meats

Clostridium botulinum

12-72 hour Days-months Blurred vision paralysis

Home-canned foods fermented fish

Staphylococcus aureus

1-6 hour 1-2 Days Gastroenteritis particularly nausea

Meats potato amp pork unpasteurized dairy products

Yersinia enterocolitica

1-2 Days 1-3 weeks Gastroenteritis appendicitis-like syndrome

Undercooked pork unpasteurized dairy products

2525

ViralViral Typical incubation period

Duration Typical clinical presentation

Assorted foods

Norovirus 1-2 Days 12-60 Hr Gastroenteritis

Under

cooked shellfish

Hepatitis A virus

15-50 Days

Weeks-months

Hepatitis Produce undercooked shellfish

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

1414

What Are the What Are the Most CommonMost Common Causes of Causes of foodborne Illnessfoodborne Illness

Those caused by the bacteriaThose caused by the bacteriabull CampylobacterCampylobacterbull SalmonellaSalmonellabull E coli O157H7E coli O157H7

Those caused by a group of virusesThose caused by a group of virusesbull Norwalk and Norwalk-like viruses Norwalk and Norwalk-like viruses

1515

Infectious Non-infectiousInfectious Non-infectious

Bacterial Virus protozoaeBacterial Virus protozoae

Biological Biological NonbiologicalNonbiological

Causes of foodborne diseaseCauses of foodborne disease

1616

Infectious causes of food poisoningInfectious causes of food poisoning

BacteriaBacteria Salmonella species Campylobacter jejuni Staphylococcus aureus Clostridium perfringens Clostridium botulinum Bacillus and other sporing

bacilli Shigella species Ecoli Yersinia enterocolitica Vibrio parahaemolyticus Aeromonas hydrophilia Streptococcus species

Group C E and G The other eg Listeria

monocytogens

Virusesa- Hepatitis Ab- Hepatitis Ec- Smal lrounded structured viruses(SRSV)eg

Norovirus CalicivirusesAstrovirusesRotaviruses

Protozoae Protozoae 1- Giardiasis2- Amoebiasis3 Cryptosporiosis4- Isospora5- Balantidum6- Blastocytosis

hominis7- Microsporidia8- Toxoplasmosis

()

1717

Causes Of foodborneCauses Of foodborne

VirusesVirusesUnlike bacteria viruses do not multiply in FoodsAcquired by

a- Primary contamination From shell Fish From Oysters From Mussels From Vegetables eg Hepatitis A From Vegetables irrigated by untreated water

b- Secondary contamination From Food handlers eg Hepatitis A

1818

Non infective causes of food poisoning

Physical Physical contaminationcontamination- - objects falling in objects falling in to food ndash metal to food ndash metal glass packaging glass packaging materials etcmaterials etc

Chemical Chemical contaminationcontamination- - Bleach cleaning Bleach cleaning chemicals chemicals getting in to food getting in to food heavy metalsheavy metals

Natural Natural contaminationcontamination Poisonous plants Poisonous plants and berries and berries undercooked red undercooked red kidney beanskidney beans

Non biological Biological

1919

Causes of foodborne Diseases (ContinuedCauses of foodborne Diseases (Continued

Biological FromBiological Froma- Mushroomsa- Mushrooms

b- Harmful algal speciesb- Harmful algal species

c- Fish c- Fish egeg Ciguatera Fish poisoningCiguatera Fish poisoning Scombroid Fish poisoning associated with Scombroid Fish poisoning associated with

raised Histamine levelsraised Histamine levels Paralytic shell Fish poisoningParalytic shell Fish poisoning

2020

2121

bull 1- Bovine tuberculosis (milk)bull 2- Brucellosis (milk)bull 3- Toxoplasmosis (meat)bull 4- Listerosis (milk products)bull 5- Mad cow diseases virus etc

Some Diseases Which Are Transmitted By Some Diseases Which Are Transmitted By Food But Not Considered As Food Food But Not Considered As Food PoisoningPoisoning

2222

Exotoxins bull Produced inside bacteria and secreted ndash Enterotoxin Neurotoxin Cardiotoxin

bull Superantigen Type I1048774intense immune response1048774cytokines1048774fever nausea vomitting shock (Staph aureus)

bull Membrane disrupting toxin Type II1048774 lysis of cells by disrupting membrane

bull A-B toxins Type III has two parts ndash A is active enzyme toxin that inhibits protein

synthesis and kills cell ndash B binds to surface so toxin is transported across plasma membrane (Clostridium

2323

Selected Clinical and Epidemiologic Characteristics of Typical Illness Caused By Common foodbornee Pathogens

Pathogen Typical Incubation Period

Duration Typical Clinical Presentation

Assorted Foods

Bacterial Salmonella species

1-3 Days 4-7 Days Gastroenteritis Undercooked eggs or poultry produce

Campylobacter jejuni

2-5 Days 2-10 Days

Gastroenteritis Undercooked poultry unpasteurized

dairy products E coli Enterotoxigenic

1-3 Days 3-7 Days Gastroenteritis Many foods

Shigella species 1-2 Days 4-7 Days Gastroenteritis Produce egg salad

2424

Listeria monocytogenes

2-6 weeks Variable Gastroenteritis meningitis abortion

Deli meat hotdogs unpasteurized dairy products

Bacillus cereus 1-6 hour lt24 hour Vomiting Gastroenteritis

Fried rice meats

Clostridium botulinum

12-72 hour Days-months Blurred vision paralysis

Home-canned foods fermented fish

Staphylococcus aureus

1-6 hour 1-2 Days Gastroenteritis particularly nausea

Meats potato amp pork unpasteurized dairy products

Yersinia enterocolitica

1-2 Days 1-3 weeks Gastroenteritis appendicitis-like syndrome

Undercooked pork unpasteurized dairy products

2525

ViralViral Typical incubation period

Duration Typical clinical presentation

Assorted foods

Norovirus 1-2 Days 12-60 Hr Gastroenteritis

Under

cooked shellfish

Hepatitis A virus

15-50 Days

Weeks-months

Hepatitis Produce undercooked shellfish

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

1515

Infectious Non-infectiousInfectious Non-infectious

Bacterial Virus protozoaeBacterial Virus protozoae

Biological Biological NonbiologicalNonbiological

Causes of foodborne diseaseCauses of foodborne disease

1616

Infectious causes of food poisoningInfectious causes of food poisoning

BacteriaBacteria Salmonella species Campylobacter jejuni Staphylococcus aureus Clostridium perfringens Clostridium botulinum Bacillus and other sporing

bacilli Shigella species Ecoli Yersinia enterocolitica Vibrio parahaemolyticus Aeromonas hydrophilia Streptococcus species

Group C E and G The other eg Listeria

monocytogens

Virusesa- Hepatitis Ab- Hepatitis Ec- Smal lrounded structured viruses(SRSV)eg

Norovirus CalicivirusesAstrovirusesRotaviruses

Protozoae Protozoae 1- Giardiasis2- Amoebiasis3 Cryptosporiosis4- Isospora5- Balantidum6- Blastocytosis

hominis7- Microsporidia8- Toxoplasmosis

()

1717

Causes Of foodborneCauses Of foodborne

VirusesVirusesUnlike bacteria viruses do not multiply in FoodsAcquired by

a- Primary contamination From shell Fish From Oysters From Mussels From Vegetables eg Hepatitis A From Vegetables irrigated by untreated water

b- Secondary contamination From Food handlers eg Hepatitis A

1818

Non infective causes of food poisoning

Physical Physical contaminationcontamination- - objects falling in objects falling in to food ndash metal to food ndash metal glass packaging glass packaging materials etcmaterials etc

Chemical Chemical contaminationcontamination- - Bleach cleaning Bleach cleaning chemicals chemicals getting in to food getting in to food heavy metalsheavy metals

Natural Natural contaminationcontamination Poisonous plants Poisonous plants and berries and berries undercooked red undercooked red kidney beanskidney beans

Non biological Biological

1919

Causes of foodborne Diseases (ContinuedCauses of foodborne Diseases (Continued

Biological FromBiological Froma- Mushroomsa- Mushrooms

b- Harmful algal speciesb- Harmful algal species

c- Fish c- Fish egeg Ciguatera Fish poisoningCiguatera Fish poisoning Scombroid Fish poisoning associated with Scombroid Fish poisoning associated with

raised Histamine levelsraised Histamine levels Paralytic shell Fish poisoningParalytic shell Fish poisoning

2020

2121

bull 1- Bovine tuberculosis (milk)bull 2- Brucellosis (milk)bull 3- Toxoplasmosis (meat)bull 4- Listerosis (milk products)bull 5- Mad cow diseases virus etc

Some Diseases Which Are Transmitted By Some Diseases Which Are Transmitted By Food But Not Considered As Food Food But Not Considered As Food PoisoningPoisoning

2222

Exotoxins bull Produced inside bacteria and secreted ndash Enterotoxin Neurotoxin Cardiotoxin

bull Superantigen Type I1048774intense immune response1048774cytokines1048774fever nausea vomitting shock (Staph aureus)

bull Membrane disrupting toxin Type II1048774 lysis of cells by disrupting membrane

bull A-B toxins Type III has two parts ndash A is active enzyme toxin that inhibits protein

synthesis and kills cell ndash B binds to surface so toxin is transported across plasma membrane (Clostridium

2323

Selected Clinical and Epidemiologic Characteristics of Typical Illness Caused By Common foodbornee Pathogens

Pathogen Typical Incubation Period

Duration Typical Clinical Presentation

Assorted Foods

Bacterial Salmonella species

1-3 Days 4-7 Days Gastroenteritis Undercooked eggs or poultry produce

Campylobacter jejuni

2-5 Days 2-10 Days

Gastroenteritis Undercooked poultry unpasteurized

dairy products E coli Enterotoxigenic

1-3 Days 3-7 Days Gastroenteritis Many foods

Shigella species 1-2 Days 4-7 Days Gastroenteritis Produce egg salad

2424

Listeria monocytogenes

2-6 weeks Variable Gastroenteritis meningitis abortion

Deli meat hotdogs unpasteurized dairy products

Bacillus cereus 1-6 hour lt24 hour Vomiting Gastroenteritis

Fried rice meats

Clostridium botulinum

12-72 hour Days-months Blurred vision paralysis

Home-canned foods fermented fish

Staphylococcus aureus

1-6 hour 1-2 Days Gastroenteritis particularly nausea

Meats potato amp pork unpasteurized dairy products

Yersinia enterocolitica

1-2 Days 1-3 weeks Gastroenteritis appendicitis-like syndrome

Undercooked pork unpasteurized dairy products

2525

ViralViral Typical incubation period

Duration Typical clinical presentation

Assorted foods

Norovirus 1-2 Days 12-60 Hr Gastroenteritis

Under

cooked shellfish

Hepatitis A virus

15-50 Days

Weeks-months

Hepatitis Produce undercooked shellfish

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

1616

Infectious causes of food poisoningInfectious causes of food poisoning

BacteriaBacteria Salmonella species Campylobacter jejuni Staphylococcus aureus Clostridium perfringens Clostridium botulinum Bacillus and other sporing

bacilli Shigella species Ecoli Yersinia enterocolitica Vibrio parahaemolyticus Aeromonas hydrophilia Streptococcus species

Group C E and G The other eg Listeria

monocytogens

Virusesa- Hepatitis Ab- Hepatitis Ec- Smal lrounded structured viruses(SRSV)eg

Norovirus CalicivirusesAstrovirusesRotaviruses

Protozoae Protozoae 1- Giardiasis2- Amoebiasis3 Cryptosporiosis4- Isospora5- Balantidum6- Blastocytosis

hominis7- Microsporidia8- Toxoplasmosis

()

1717

Causes Of foodborneCauses Of foodborne

VirusesVirusesUnlike bacteria viruses do not multiply in FoodsAcquired by

a- Primary contamination From shell Fish From Oysters From Mussels From Vegetables eg Hepatitis A From Vegetables irrigated by untreated water

b- Secondary contamination From Food handlers eg Hepatitis A

1818

Non infective causes of food poisoning

Physical Physical contaminationcontamination- - objects falling in objects falling in to food ndash metal to food ndash metal glass packaging glass packaging materials etcmaterials etc

Chemical Chemical contaminationcontamination- - Bleach cleaning Bleach cleaning chemicals chemicals getting in to food getting in to food heavy metalsheavy metals

Natural Natural contaminationcontamination Poisonous plants Poisonous plants and berries and berries undercooked red undercooked red kidney beanskidney beans

Non biological Biological

1919

Causes of foodborne Diseases (ContinuedCauses of foodborne Diseases (Continued

Biological FromBiological Froma- Mushroomsa- Mushrooms

b- Harmful algal speciesb- Harmful algal species

c- Fish c- Fish egeg Ciguatera Fish poisoningCiguatera Fish poisoning Scombroid Fish poisoning associated with Scombroid Fish poisoning associated with

raised Histamine levelsraised Histamine levels Paralytic shell Fish poisoningParalytic shell Fish poisoning

2020

2121

bull 1- Bovine tuberculosis (milk)bull 2- Brucellosis (milk)bull 3- Toxoplasmosis (meat)bull 4- Listerosis (milk products)bull 5- Mad cow diseases virus etc

Some Diseases Which Are Transmitted By Some Diseases Which Are Transmitted By Food But Not Considered As Food Food But Not Considered As Food PoisoningPoisoning

2222

Exotoxins bull Produced inside bacteria and secreted ndash Enterotoxin Neurotoxin Cardiotoxin

bull Superantigen Type I1048774intense immune response1048774cytokines1048774fever nausea vomitting shock (Staph aureus)

bull Membrane disrupting toxin Type II1048774 lysis of cells by disrupting membrane

bull A-B toxins Type III has two parts ndash A is active enzyme toxin that inhibits protein

synthesis and kills cell ndash B binds to surface so toxin is transported across plasma membrane (Clostridium

2323

Selected Clinical and Epidemiologic Characteristics of Typical Illness Caused By Common foodbornee Pathogens

Pathogen Typical Incubation Period

Duration Typical Clinical Presentation

Assorted Foods

Bacterial Salmonella species

1-3 Days 4-7 Days Gastroenteritis Undercooked eggs or poultry produce

Campylobacter jejuni

2-5 Days 2-10 Days

Gastroenteritis Undercooked poultry unpasteurized

dairy products E coli Enterotoxigenic

1-3 Days 3-7 Days Gastroenteritis Many foods

Shigella species 1-2 Days 4-7 Days Gastroenteritis Produce egg salad

2424

Listeria monocytogenes

2-6 weeks Variable Gastroenteritis meningitis abortion

Deli meat hotdogs unpasteurized dairy products

Bacillus cereus 1-6 hour lt24 hour Vomiting Gastroenteritis

Fried rice meats

Clostridium botulinum

12-72 hour Days-months Blurred vision paralysis

Home-canned foods fermented fish

Staphylococcus aureus

1-6 hour 1-2 Days Gastroenteritis particularly nausea

Meats potato amp pork unpasteurized dairy products

Yersinia enterocolitica

1-2 Days 1-3 weeks Gastroenteritis appendicitis-like syndrome

Undercooked pork unpasteurized dairy products

2525

ViralViral Typical incubation period

Duration Typical clinical presentation

Assorted foods

Norovirus 1-2 Days 12-60 Hr Gastroenteritis

Under

cooked shellfish

Hepatitis A virus

15-50 Days

Weeks-months

Hepatitis Produce undercooked shellfish

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

1717

Causes Of foodborneCauses Of foodborne

VirusesVirusesUnlike bacteria viruses do not multiply in FoodsAcquired by

a- Primary contamination From shell Fish From Oysters From Mussels From Vegetables eg Hepatitis A From Vegetables irrigated by untreated water

b- Secondary contamination From Food handlers eg Hepatitis A

1818

Non infective causes of food poisoning

Physical Physical contaminationcontamination- - objects falling in objects falling in to food ndash metal to food ndash metal glass packaging glass packaging materials etcmaterials etc

Chemical Chemical contaminationcontamination- - Bleach cleaning Bleach cleaning chemicals chemicals getting in to food getting in to food heavy metalsheavy metals

Natural Natural contaminationcontamination Poisonous plants Poisonous plants and berries and berries undercooked red undercooked red kidney beanskidney beans

Non biological Biological

1919

Causes of foodborne Diseases (ContinuedCauses of foodborne Diseases (Continued

Biological FromBiological Froma- Mushroomsa- Mushrooms

b- Harmful algal speciesb- Harmful algal species

c- Fish c- Fish egeg Ciguatera Fish poisoningCiguatera Fish poisoning Scombroid Fish poisoning associated with Scombroid Fish poisoning associated with

raised Histamine levelsraised Histamine levels Paralytic shell Fish poisoningParalytic shell Fish poisoning

2020

2121

bull 1- Bovine tuberculosis (milk)bull 2- Brucellosis (milk)bull 3- Toxoplasmosis (meat)bull 4- Listerosis (milk products)bull 5- Mad cow diseases virus etc

Some Diseases Which Are Transmitted By Some Diseases Which Are Transmitted By Food But Not Considered As Food Food But Not Considered As Food PoisoningPoisoning

2222

Exotoxins bull Produced inside bacteria and secreted ndash Enterotoxin Neurotoxin Cardiotoxin

bull Superantigen Type I1048774intense immune response1048774cytokines1048774fever nausea vomitting shock (Staph aureus)

bull Membrane disrupting toxin Type II1048774 lysis of cells by disrupting membrane

bull A-B toxins Type III has two parts ndash A is active enzyme toxin that inhibits protein

synthesis and kills cell ndash B binds to surface so toxin is transported across plasma membrane (Clostridium

2323

Selected Clinical and Epidemiologic Characteristics of Typical Illness Caused By Common foodbornee Pathogens

Pathogen Typical Incubation Period

Duration Typical Clinical Presentation

Assorted Foods

Bacterial Salmonella species

1-3 Days 4-7 Days Gastroenteritis Undercooked eggs or poultry produce

Campylobacter jejuni

2-5 Days 2-10 Days

Gastroenteritis Undercooked poultry unpasteurized

dairy products E coli Enterotoxigenic

1-3 Days 3-7 Days Gastroenteritis Many foods

Shigella species 1-2 Days 4-7 Days Gastroenteritis Produce egg salad

2424

Listeria monocytogenes

2-6 weeks Variable Gastroenteritis meningitis abortion

Deli meat hotdogs unpasteurized dairy products

Bacillus cereus 1-6 hour lt24 hour Vomiting Gastroenteritis

Fried rice meats

Clostridium botulinum

12-72 hour Days-months Blurred vision paralysis

Home-canned foods fermented fish

Staphylococcus aureus

1-6 hour 1-2 Days Gastroenteritis particularly nausea

Meats potato amp pork unpasteurized dairy products

Yersinia enterocolitica

1-2 Days 1-3 weeks Gastroenteritis appendicitis-like syndrome

Undercooked pork unpasteurized dairy products

2525

ViralViral Typical incubation period

Duration Typical clinical presentation

Assorted foods

Norovirus 1-2 Days 12-60 Hr Gastroenteritis

Under

cooked shellfish

Hepatitis A virus

15-50 Days

Weeks-months

Hepatitis Produce undercooked shellfish

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

1818

Non infective causes of food poisoning

Physical Physical contaminationcontamination- - objects falling in objects falling in to food ndash metal to food ndash metal glass packaging glass packaging materials etcmaterials etc

Chemical Chemical contaminationcontamination- - Bleach cleaning Bleach cleaning chemicals chemicals getting in to food getting in to food heavy metalsheavy metals

Natural Natural contaminationcontamination Poisonous plants Poisonous plants and berries and berries undercooked red undercooked red kidney beanskidney beans

Non biological Biological

1919

Causes of foodborne Diseases (ContinuedCauses of foodborne Diseases (Continued

Biological FromBiological Froma- Mushroomsa- Mushrooms

b- Harmful algal speciesb- Harmful algal species

c- Fish c- Fish egeg Ciguatera Fish poisoningCiguatera Fish poisoning Scombroid Fish poisoning associated with Scombroid Fish poisoning associated with

raised Histamine levelsraised Histamine levels Paralytic shell Fish poisoningParalytic shell Fish poisoning

2020

2121

bull 1- Bovine tuberculosis (milk)bull 2- Brucellosis (milk)bull 3- Toxoplasmosis (meat)bull 4- Listerosis (milk products)bull 5- Mad cow diseases virus etc

Some Diseases Which Are Transmitted By Some Diseases Which Are Transmitted By Food But Not Considered As Food Food But Not Considered As Food PoisoningPoisoning

2222

Exotoxins bull Produced inside bacteria and secreted ndash Enterotoxin Neurotoxin Cardiotoxin

bull Superantigen Type I1048774intense immune response1048774cytokines1048774fever nausea vomitting shock (Staph aureus)

bull Membrane disrupting toxin Type II1048774 lysis of cells by disrupting membrane

bull A-B toxins Type III has two parts ndash A is active enzyme toxin that inhibits protein

synthesis and kills cell ndash B binds to surface so toxin is transported across plasma membrane (Clostridium

2323

Selected Clinical and Epidemiologic Characteristics of Typical Illness Caused By Common foodbornee Pathogens

Pathogen Typical Incubation Period

Duration Typical Clinical Presentation

Assorted Foods

Bacterial Salmonella species

1-3 Days 4-7 Days Gastroenteritis Undercooked eggs or poultry produce

Campylobacter jejuni

2-5 Days 2-10 Days

Gastroenteritis Undercooked poultry unpasteurized

dairy products E coli Enterotoxigenic

1-3 Days 3-7 Days Gastroenteritis Many foods

Shigella species 1-2 Days 4-7 Days Gastroenteritis Produce egg salad

2424

Listeria monocytogenes

2-6 weeks Variable Gastroenteritis meningitis abortion

Deli meat hotdogs unpasteurized dairy products

Bacillus cereus 1-6 hour lt24 hour Vomiting Gastroenteritis

Fried rice meats

Clostridium botulinum

12-72 hour Days-months Blurred vision paralysis

Home-canned foods fermented fish

Staphylococcus aureus

1-6 hour 1-2 Days Gastroenteritis particularly nausea

Meats potato amp pork unpasteurized dairy products

Yersinia enterocolitica

1-2 Days 1-3 weeks Gastroenteritis appendicitis-like syndrome

Undercooked pork unpasteurized dairy products

2525

ViralViral Typical incubation period

Duration Typical clinical presentation

Assorted foods

Norovirus 1-2 Days 12-60 Hr Gastroenteritis

Under

cooked shellfish

Hepatitis A virus

15-50 Days

Weeks-months

Hepatitis Produce undercooked shellfish

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

1919

Causes of foodborne Diseases (ContinuedCauses of foodborne Diseases (Continued

Biological FromBiological Froma- Mushroomsa- Mushrooms

b- Harmful algal speciesb- Harmful algal species

c- Fish c- Fish egeg Ciguatera Fish poisoningCiguatera Fish poisoning Scombroid Fish poisoning associated with Scombroid Fish poisoning associated with

raised Histamine levelsraised Histamine levels Paralytic shell Fish poisoningParalytic shell Fish poisoning

2020

2121

bull 1- Bovine tuberculosis (milk)bull 2- Brucellosis (milk)bull 3- Toxoplasmosis (meat)bull 4- Listerosis (milk products)bull 5- Mad cow diseases virus etc

Some Diseases Which Are Transmitted By Some Diseases Which Are Transmitted By Food But Not Considered As Food Food But Not Considered As Food PoisoningPoisoning

2222

Exotoxins bull Produced inside bacteria and secreted ndash Enterotoxin Neurotoxin Cardiotoxin

bull Superantigen Type I1048774intense immune response1048774cytokines1048774fever nausea vomitting shock (Staph aureus)

bull Membrane disrupting toxin Type II1048774 lysis of cells by disrupting membrane

bull A-B toxins Type III has two parts ndash A is active enzyme toxin that inhibits protein

synthesis and kills cell ndash B binds to surface so toxin is transported across plasma membrane (Clostridium

2323

Selected Clinical and Epidemiologic Characteristics of Typical Illness Caused By Common foodbornee Pathogens

Pathogen Typical Incubation Period

Duration Typical Clinical Presentation

Assorted Foods

Bacterial Salmonella species

1-3 Days 4-7 Days Gastroenteritis Undercooked eggs or poultry produce

Campylobacter jejuni

2-5 Days 2-10 Days

Gastroenteritis Undercooked poultry unpasteurized

dairy products E coli Enterotoxigenic

1-3 Days 3-7 Days Gastroenteritis Many foods

Shigella species 1-2 Days 4-7 Days Gastroenteritis Produce egg salad

2424

Listeria monocytogenes

2-6 weeks Variable Gastroenteritis meningitis abortion

Deli meat hotdogs unpasteurized dairy products

Bacillus cereus 1-6 hour lt24 hour Vomiting Gastroenteritis

Fried rice meats

Clostridium botulinum

12-72 hour Days-months Blurred vision paralysis

Home-canned foods fermented fish

Staphylococcus aureus

1-6 hour 1-2 Days Gastroenteritis particularly nausea

Meats potato amp pork unpasteurized dairy products

Yersinia enterocolitica

1-2 Days 1-3 weeks Gastroenteritis appendicitis-like syndrome

Undercooked pork unpasteurized dairy products

2525

ViralViral Typical incubation period

Duration Typical clinical presentation

Assorted foods

Norovirus 1-2 Days 12-60 Hr Gastroenteritis

Under

cooked shellfish

Hepatitis A virus

15-50 Days

Weeks-months

Hepatitis Produce undercooked shellfish

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

2020

2121

bull 1- Bovine tuberculosis (milk)bull 2- Brucellosis (milk)bull 3- Toxoplasmosis (meat)bull 4- Listerosis (milk products)bull 5- Mad cow diseases virus etc

Some Diseases Which Are Transmitted By Some Diseases Which Are Transmitted By Food But Not Considered As Food Food But Not Considered As Food PoisoningPoisoning

2222

Exotoxins bull Produced inside bacteria and secreted ndash Enterotoxin Neurotoxin Cardiotoxin

bull Superantigen Type I1048774intense immune response1048774cytokines1048774fever nausea vomitting shock (Staph aureus)

bull Membrane disrupting toxin Type II1048774 lysis of cells by disrupting membrane

bull A-B toxins Type III has two parts ndash A is active enzyme toxin that inhibits protein

synthesis and kills cell ndash B binds to surface so toxin is transported across plasma membrane (Clostridium

2323

Selected Clinical and Epidemiologic Characteristics of Typical Illness Caused By Common foodbornee Pathogens

Pathogen Typical Incubation Period

Duration Typical Clinical Presentation

Assorted Foods

Bacterial Salmonella species

1-3 Days 4-7 Days Gastroenteritis Undercooked eggs or poultry produce

Campylobacter jejuni

2-5 Days 2-10 Days

Gastroenteritis Undercooked poultry unpasteurized

dairy products E coli Enterotoxigenic

1-3 Days 3-7 Days Gastroenteritis Many foods

Shigella species 1-2 Days 4-7 Days Gastroenteritis Produce egg salad

2424

Listeria monocytogenes

2-6 weeks Variable Gastroenteritis meningitis abortion

Deli meat hotdogs unpasteurized dairy products

Bacillus cereus 1-6 hour lt24 hour Vomiting Gastroenteritis

Fried rice meats

Clostridium botulinum

12-72 hour Days-months Blurred vision paralysis

Home-canned foods fermented fish

Staphylococcus aureus

1-6 hour 1-2 Days Gastroenteritis particularly nausea

Meats potato amp pork unpasteurized dairy products

Yersinia enterocolitica

1-2 Days 1-3 weeks Gastroenteritis appendicitis-like syndrome

Undercooked pork unpasteurized dairy products

2525

ViralViral Typical incubation period

Duration Typical clinical presentation

Assorted foods

Norovirus 1-2 Days 12-60 Hr Gastroenteritis

Under

cooked shellfish

Hepatitis A virus

15-50 Days

Weeks-months

Hepatitis Produce undercooked shellfish

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

2121

bull 1- Bovine tuberculosis (milk)bull 2- Brucellosis (milk)bull 3- Toxoplasmosis (meat)bull 4- Listerosis (milk products)bull 5- Mad cow diseases virus etc

Some Diseases Which Are Transmitted By Some Diseases Which Are Transmitted By Food But Not Considered As Food Food But Not Considered As Food PoisoningPoisoning

2222

Exotoxins bull Produced inside bacteria and secreted ndash Enterotoxin Neurotoxin Cardiotoxin

bull Superantigen Type I1048774intense immune response1048774cytokines1048774fever nausea vomitting shock (Staph aureus)

bull Membrane disrupting toxin Type II1048774 lysis of cells by disrupting membrane

bull A-B toxins Type III has two parts ndash A is active enzyme toxin that inhibits protein

synthesis and kills cell ndash B binds to surface so toxin is transported across plasma membrane (Clostridium

2323

Selected Clinical and Epidemiologic Characteristics of Typical Illness Caused By Common foodbornee Pathogens

Pathogen Typical Incubation Period

Duration Typical Clinical Presentation

Assorted Foods

Bacterial Salmonella species

1-3 Days 4-7 Days Gastroenteritis Undercooked eggs or poultry produce

Campylobacter jejuni

2-5 Days 2-10 Days

Gastroenteritis Undercooked poultry unpasteurized

dairy products E coli Enterotoxigenic

1-3 Days 3-7 Days Gastroenteritis Many foods

Shigella species 1-2 Days 4-7 Days Gastroenteritis Produce egg salad

2424

Listeria monocytogenes

2-6 weeks Variable Gastroenteritis meningitis abortion

Deli meat hotdogs unpasteurized dairy products

Bacillus cereus 1-6 hour lt24 hour Vomiting Gastroenteritis

Fried rice meats

Clostridium botulinum

12-72 hour Days-months Blurred vision paralysis

Home-canned foods fermented fish

Staphylococcus aureus

1-6 hour 1-2 Days Gastroenteritis particularly nausea

Meats potato amp pork unpasteurized dairy products

Yersinia enterocolitica

1-2 Days 1-3 weeks Gastroenteritis appendicitis-like syndrome

Undercooked pork unpasteurized dairy products

2525

ViralViral Typical incubation period

Duration Typical clinical presentation

Assorted foods

Norovirus 1-2 Days 12-60 Hr Gastroenteritis

Under

cooked shellfish

Hepatitis A virus

15-50 Days

Weeks-months

Hepatitis Produce undercooked shellfish

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

2222

Exotoxins bull Produced inside bacteria and secreted ndash Enterotoxin Neurotoxin Cardiotoxin

bull Superantigen Type I1048774intense immune response1048774cytokines1048774fever nausea vomitting shock (Staph aureus)

bull Membrane disrupting toxin Type II1048774 lysis of cells by disrupting membrane

bull A-B toxins Type III has two parts ndash A is active enzyme toxin that inhibits protein

synthesis and kills cell ndash B binds to surface so toxin is transported across plasma membrane (Clostridium

2323

Selected Clinical and Epidemiologic Characteristics of Typical Illness Caused By Common foodbornee Pathogens

Pathogen Typical Incubation Period

Duration Typical Clinical Presentation

Assorted Foods

Bacterial Salmonella species

1-3 Days 4-7 Days Gastroenteritis Undercooked eggs or poultry produce

Campylobacter jejuni

2-5 Days 2-10 Days

Gastroenteritis Undercooked poultry unpasteurized

dairy products E coli Enterotoxigenic

1-3 Days 3-7 Days Gastroenteritis Many foods

Shigella species 1-2 Days 4-7 Days Gastroenteritis Produce egg salad

2424

Listeria monocytogenes

2-6 weeks Variable Gastroenteritis meningitis abortion

Deli meat hotdogs unpasteurized dairy products

Bacillus cereus 1-6 hour lt24 hour Vomiting Gastroenteritis

Fried rice meats

Clostridium botulinum

12-72 hour Days-months Blurred vision paralysis

Home-canned foods fermented fish

Staphylococcus aureus

1-6 hour 1-2 Days Gastroenteritis particularly nausea

Meats potato amp pork unpasteurized dairy products

Yersinia enterocolitica

1-2 Days 1-3 weeks Gastroenteritis appendicitis-like syndrome

Undercooked pork unpasteurized dairy products

2525

ViralViral Typical incubation period

Duration Typical clinical presentation

Assorted foods

Norovirus 1-2 Days 12-60 Hr Gastroenteritis

Under

cooked shellfish

Hepatitis A virus

15-50 Days

Weeks-months

Hepatitis Produce undercooked shellfish

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

2323

Selected Clinical and Epidemiologic Characteristics of Typical Illness Caused By Common foodbornee Pathogens

Pathogen Typical Incubation Period

Duration Typical Clinical Presentation

Assorted Foods

Bacterial Salmonella species

1-3 Days 4-7 Days Gastroenteritis Undercooked eggs or poultry produce

Campylobacter jejuni

2-5 Days 2-10 Days

Gastroenteritis Undercooked poultry unpasteurized

dairy products E coli Enterotoxigenic

1-3 Days 3-7 Days Gastroenteritis Many foods

Shigella species 1-2 Days 4-7 Days Gastroenteritis Produce egg salad

2424

Listeria monocytogenes

2-6 weeks Variable Gastroenteritis meningitis abortion

Deli meat hotdogs unpasteurized dairy products

Bacillus cereus 1-6 hour lt24 hour Vomiting Gastroenteritis

Fried rice meats

Clostridium botulinum

12-72 hour Days-months Blurred vision paralysis

Home-canned foods fermented fish

Staphylococcus aureus

1-6 hour 1-2 Days Gastroenteritis particularly nausea

Meats potato amp pork unpasteurized dairy products

Yersinia enterocolitica

1-2 Days 1-3 weeks Gastroenteritis appendicitis-like syndrome

Undercooked pork unpasteurized dairy products

2525

ViralViral Typical incubation period

Duration Typical clinical presentation

Assorted foods

Norovirus 1-2 Days 12-60 Hr Gastroenteritis

Under

cooked shellfish

Hepatitis A virus

15-50 Days

Weeks-months

Hepatitis Produce undercooked shellfish

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

2424

Listeria monocytogenes

2-6 weeks Variable Gastroenteritis meningitis abortion

Deli meat hotdogs unpasteurized dairy products

Bacillus cereus 1-6 hour lt24 hour Vomiting Gastroenteritis

Fried rice meats

Clostridium botulinum

12-72 hour Days-months Blurred vision paralysis

Home-canned foods fermented fish

Staphylococcus aureus

1-6 hour 1-2 Days Gastroenteritis particularly nausea

Meats potato amp pork unpasteurized dairy products

Yersinia enterocolitica

1-2 Days 1-3 weeks Gastroenteritis appendicitis-like syndrome

Undercooked pork unpasteurized dairy products

2525

ViralViral Typical incubation period

Duration Typical clinical presentation

Assorted foods

Norovirus 1-2 Days 12-60 Hr Gastroenteritis

Under

cooked shellfish

Hepatitis A virus

15-50 Days

Weeks-months

Hepatitis Produce undercooked shellfish

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

2525

ViralViral Typical incubation period

Duration Typical clinical presentation

Assorted foods

Norovirus 1-2 Days 12-60 Hr Gastroenteritis

Under

cooked shellfish

Hepatitis A virus

15-50 Days

Weeks-months

Hepatitis Produce undercooked shellfish

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

2626

ParasiticParasitic Typical incubation

Duration Typical clinical presentation

Assorted foods

Cryptos

poridium parvum

2-10 Days Weeks Gastroenteritis Produce water

Cyclospora cayetanesis

1-11 Days Weeks Gastroenteritis Produce water

Toxoplasma gondii

5-23 Days Months Influenza-like illness

lymphadenopathy

Food contaminated by cat feces undercooked

meat Giardia lamblia

1-4 Wk Weeks Gastroenteritis Water

Taenia solium Variable Variable Asymptomatic cysticercosis

Raw pork

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

2727

Important Microbial Causes of Food PoisoningImportant Microbial Causes of Food Poisoning Toxin related Toxin related A Staphylococcus aureus A Staphylococcus aureus 24hourFlu incubation period lt 6 hoursincubation period lt 6 hours

An intoxication Not infectionAn intoxication Not infectionClinical Features appear 1-6 hours after ingestion

and include vomiting (V) diarrhea (D) and intense abdominal paincramping (AB) usually no fever

-last approximately 24 hours

Source infected human amp food handlers

Food contaminated -- enterotoxin produced-toxin is heat stable

Diagnosis

1-epidemiological

2-isolating organism

from suspected food

3- toxin detection in feacesof patient

Treatment ndashnone

supportive

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

2828

SaureusSaureus

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

2929

B- Bacillus cereus (from rice meals)Bacillus caereus is an spore forming aerobic

bacillus produces two types of enterotoxins

a- Heat stable causing emetic type of food poisoning incubation period lt 6 hours vomiting nausea

b- Heat labile causing diarrheal type incubation period 6-24 hours

ldquoBOTH TOXINS ARE PREFORMED IN FOODrdquo

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

3030

Clostridium PerfringensClostridium Perfringens Causative agent type A strains of C perfringens (C

Welchii) Gram positive anaerobic rod spore forming characterized

by sudden Onset of colic Diarrhea NauseaPathogenesisPathogenesis

Incubation period 10-16 hours Spore-vegetate in food when swollen they sporulate in the

intestine and Produce toxinDiagnosis Detection of spores in food gt105 spores Detection of spore in faeces gt106 spores

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

3131

Botulism Clostridium botulinumbullGram positive anaerobic spore forming Gram positive anaerobic spore forming It produces a powerful It produces a powerful

toxin The most lethal (killing toxin) toxin The most lethal (killing toxin) 3 Kg can kill the whole 3 Kg can kill the whole population of the worldpopulation of the world

Foods associated home canned ldquolow acidrdquo vegetables honey

PathogenesisPathogenesis Incubation period 12-24 hours under anaerobic condition the spores germinate in the foods to produce the toxin Classified into A ndash G strains they produce the responsible

toxins A B E and F Toxin is heat labile Toxin inhibits release of acetylcholine at neurone muscular

junction leading to flaccid paralysis

Symptoms12-72 hours after ingestion neurological blurred vision and descending muscle weakness-flaccid paralysis

bull Treatment antitoxin not antibiotics

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

3232

Campylobacter jejuniCampylobacter jejuni General characteristics gram negative curved rod

microaerophile one or two polar flagella no capsule Special culture to grow 42⁰C incubator Source Part of the normal flora of poultry and dairy cattle - unpasteurized milk -undercooked poultry (shwarma)- may be found at a

concentration of 109cellsgram of chicken

Incubation period 2-5 days

bull Symptoms Person to person D (which may be bloody) ABfever (1040C) vomiting uncommon ndash Last 2-10 days ndash Some cases lead to Guillen-Barre syndrome and Rheumatoid Arthritis weeks Diagnosis Gram stain of feaces shows spiral organisms

Treatment none mostly supportive care -some cases require antibiotics (erythromycin quinolones)

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

3333

ListeriosisListeriosis Causative agent Listeria monocytogenes

Gram positive rod aerobic Resembles dipththeroids Can multiply at lower temperature 4degCSources Wide spread in dust soil water sewage vegetation Wide spread in dust soil water sewage vegetation

animals feeds poultry hot dogsmeat fish vegetable animals feeds poultry hot dogsmeat fish vegetable

DiseasesDiseases - Infects GI tract (usually few symptoms)penetrates mucosa amp enters blood stream

- Fourth leading cause of meningitis (perhaps 50 fatality )

-Pregnant women crosses placenta and causes febrile illness abscess in fetal tissue 1048774miscarriage or stillbirth (60 )

- Neonates ndash meningitis

- Immunocompromised patients ndash febrile illness

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

3434

SalmonellaSalmonella General characteristics gram negative rod facultative anaerobe

peritrichous flagella Caused by No typhoid causing Salmonellas (Called Food poisoning gastro intestinal Salmonellas) Causes about 85 of cases of Food poisoning or Food borne

diseases (Shawrma) SourcesSources

bull Raw poultry and eggsRaw poultry and eggsbull Raw milkRaw milkbull Raw beefRaw beefbull Unwashed fruit alfalfa sproutsUnwashed fruit alfalfa sproutsbull Reptile pets Snakes turtles lizardsReptile pets Snakes turtles lizards

Part of the normal flora of poultry reptiles

Most Salmonella killed by acid so need to ingest large numbers to survive stomach acid in order to cause infection

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

3535

Salmonella typhimurium and enteritidisndash Most common serovars in USA

ndash Antibiotics not advised due to increasingresistance (due to widespread addition ofantibiotics to animal feed)

ndash Do Not treat gastroenteritis unless invades tissues

SalmonellaCulture isolate and identify lactose negative amp H2S positive

Incubation time 12-36 hours Symptoms include D AB and a moderate fever Full recovery in a few days but may shed the organism for 6 mnths Approx 2-4 million casesyear only 40-50000 are actually reported

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

3636

ShigellaShigella

General characteristics gram negativerod facultative anaerobe lactose negative

bull Only found in the feces of other humans

bull Organisms transmitted by the five Frsquos

-food fingers feces flies and fomites

Shigellosis or bacillary dysentery

Incubation time 24-48 hours

ndash Only need 10 cells to cause infection not

affected by stomach acid

bull Symptoms F AB D (may contain blood and mucus)

bull See passage of small volume bloodystools (20day)

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

3737

Shigella

bull S sonnei-most common species in US

responsible relatively mild may cause

some of travelerrsquos diarrhea

bull S dysenteriae-causes more serious

infection dysentery

-due to the production of a Shiga toxin

(A-B toxin)

-in tropical areas-death rate up to 20

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

3838

Dysenterybull Shigella dysenteriaendash Virulent strains have plasmids to attach to epi cells of intestine membrane ruffles around and engulfs bacteria which multiply in cell and produce Shiga toxin which destroys tissue also has

mechanism that allows to spread from cell to cell sloughed areas of epis leads to intenseinflammation pus and bleeding

ndash Rarely invades blood

ndash Toxin strongly associated with hemolytic uremic syndrone RBCs break in tiny blood vessels leading

to anemia and kidney damage

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

3939

SalmonellaSalmonella ShigellaShigella

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

4040

CholeraCholera Curved gram negative rod facultative anaerobe single polar flagellabull Can exist in saltwater for extended periods of time

tolerates high pH and high salt concentrationsbull Killed by stomach acid so need large numbers of

organisms to cause infection

Incubation time several hours to days

bull Symptoms ldquorice water stoolsrdquo suddenonset of explosive watery diarrhea (up to20 litersday) with vomiting and pain

bull Cholera toxin is the key pathogenic featurendash A-B toxin causes activation on enzyme that causes

cells to continuously secrete chlorideions and electrolytes and H2O1048774 watery diarrhea

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

4141

Non-cholera Vibriosbull V parahemolyticus halophilic (requires sodium) Inhabits coastal salt waters usually transmitted by raw or undercooked shellfish less severe gastroenteritis

bull V vulnificus halophilic (requires 1 NaCl) wound infectionsmdashminor skin infection in coastal

water1048774rapid sread through tissues1048774possible amputationndash Fatal specticemia in 50 of patients with liver

disease

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

4242

Escherichia colibull Normal bowel flora

bull Strains that cause GI disease have virulence factors (coded by plasmids)

ndash Enterotoxin production

ndash Abiltiy to adhere to small intestin

Diarrhea causing E coli

Classified according to virulence

ndash Entertoxigenic E coli (ETEC)

ndash Enterpathogenic E coli (EPEC)

ndash Enterohemorrhagic E coli (EHEC)

ndash Enteroinvasive E coli (EIEC)

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

4343

Entertoxigenic E coli (ETEC)

bull Also known as travelerrsquos diarrhea

bullTwo Enterotoxins promote the pumping of Cl- and inhibition of NaCl which results in diarrhea

ndash Profuse watery stools

bull No invasion

bull Can develop immunity

bull Prevent with bismuth (Pepto-Bismol)

Enterpathogenic E coli (EPEC)

bull Attacks the small intestine

bull In developing countries accounts for 20of diarrhea in bottle-fed infants

bull Attaches to mucosa of small intestine and causes cell surface changes

(loss of microvilli)

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

4444

Enteroinvasive E Coli (EIEC)

bull Invades lining Of large intestine causing

necrosis inflammation and ulceration of large bowel

bull Usually seen in children inn areas with poor sanitation

Enterohemorrhagic E coli(EHEC)bull Obtain from the consumption

of animal productsbull Small dose (lt 100 bacteria) to

infect

bull Attacks the colon

bull Produces Shiga like toxin and lesion inflammation and bleeding (hemorrhagic colitis)

bull O157H7 causes bloody diarrhea which may lead to hemolytic uremic syndrome

bull Sorbitol negative MacConkeys used to isolate

culture all bloody diarrhea

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

4545

Yersinia enterocolitica

bull Gram negative rod lactose negative grows at 4⁰C

bull Inhabits domestic animals (contaminates meat and milk)

bull Fever diarrhea abdominal pain

bull Can invade mucosa and spread to lymphatics (may present as appendicitis)bull

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

4646

Food Poisoning OutbreaksFood Poisoning Outbreaks

1Illness in a period of time - few hours few weeks1Illness in a period of time - few hours few weeks

2In individuals who consumed common food2In individuals who consumed common food

3Many acute cases can happen3Many acute cases can happen

4Proper evaluation of cases and implicated food is 4Proper evaluation of cases and implicated food is essentialessential

5Single cases are difficult to recognized unless 5Single cases are difficult to recognized unless they have a distinctive clinical syndrome they have a distinctive clinical syndrome eg eg BotulismBotulism

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

4747

LABORATORY DIAGNOSIS OF LABORATORY DIAGNOSIS OF FOOD POISONING OUTBREAKSFOOD POISONING OUTBREAKS

1- Type of Food

2-Incubation period

3-Isolation of the causative agent from

a- Patient faeces Vomit

b- From incriminated food and related articles

4- Investigation of Food Handlers in the same way

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

4848

LABORATORY INVESTIGATIONS LABORATORY INVESTIGATIONS OF FOOD HANDLERSOF FOOD HANDLERS

1-Most Important to explain the procedure

2-Donrsquot frightened the food handlers

3-Look for Salmonellae Giardia Amebae

4-Stop work until three specimens are negative

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

4949

Is it safe to eat

lsquoUse byrsquo dates are used for perishable foods

eg cheese milk

lsquoBest beforersquo dates are used for less perishable foods eg canned baked beans jar of jam and frozen fish fingers

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

5050

Where should these foods be stored

Different foods are stored in a variety of ways to keep them safe to eat for longer

Dry cupboard Refrigerator Freezer

copy British Nutrition Foundation 2003

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

5151

Raw and cooked foodsRaw meat and poultry should be stored on the bottom shelf of the fridge to prevent cross-contamination

copy British Nutrition Foundation 2003

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

5252

Fruit and vegetablesAlways wash fruit and vegetables before you eat or use them to cook

This removes dirt and otherand other particles

copy British Nutrition Foundation 2003

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

5353

PreventionPrevention Cook Cook to Proper Temperatures -

use a food thermometer to check ttemperature of food that you cook

Chill Refrigerate Promptly - keepcoldfoods cold Divide large amounts of food for quick cooling

in the refrig

Clean Wash Hands and Surfaces Often - plain soap and plenty of water scrubbing for 20 seconds

Separate Prevent Cross Contamination ndash keep raw and ready-to-eat foods away from raw meat

Store Store Foods Properly ndash checkpackage labels for use-by dates

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

5454

5555

THANK YOUTHANK YOU

5656

5757

5858

5555

THANK YOUTHANK YOU

5656

5757

5858

5656

5757

5858

5757

5858

5858