Download - MICROBIAL DISEASES OF THE DIGESTIVE SYSTEM
MICROBIAL DISEASES OF THE DIGESTIVE
SYSTEM
MOUTH• Over 300 types of bacteria• Dental caries• Periodontal disease
–Gingivitis
–Periodontitis
DENTAL CARIES• Dental plaque
–Accumulation of microorganisms and their products (dental plaque)
–Streptococcus mutans
–Actinomyces spp.
DENTAL CARIES (cont.)
• Attachment• Colonization• Sugar (glucose+fructose)• Glucose > dextran• Fructose > lactic acid
Enamel
DENTAL CARIES (cont.)• Lactic acid softens enamel• Initial, S. mutans• Advance, Lactobacillus spp.• Pulp infection
DENTAL CARIES (cont.)• Treatment
– Root canal therapy– Penicillin
• Prevention– Fluoride– Reduced sucrose in diet– Brushing and flossing– Professional cleaning
PERIODONTAL DISEASE
• Inflammation of teeth-supporting tissue• Gingivitis
– Gums inflammation (bleeding)
PERIODONTAL DISEASE (cont.)
• Streptococci, actinomyces and gram-negative bacteria
• Prevented by brushing & flossing
PERIODONTITIS• Chronic gingivitis• 10% of teeth loss• Affects bone• Surgery and cleaning
LOWER DIGESTIVE SYSTEM
• Infections
–Salmonellosis• Intoxications
–Staphylococcus aureus
Practice that contributed to food-borne disease (1988-1992)
1. Improper holding temperature2. Poor personal hygiene of food
handlers3. Food obtained from an unsafe
source was the least commonly reported factor
Syndrome
• A group of symptoms that together are characteristic of a specific disease
Gastrointestinal Syndrome• Gastroenteritis associated with
nausea, vomiting and diarrhea
Dysentery syndrome
• Any infectious disease of the large intestine marked by ulceration, hemorrhagic diarrhea with mucus and often blood
GASTROENTERITIS• Inflammation of the stomach and
intestinal mucosa
GASTROENTERITIS (cont.)
• Abdominal cramps• Nausea• Vomiting• Dehydration
GASTROENTERITIS (cont.)
• E. coli• Shigella spp.• Salmonella spp.• Campylobacter spp.• Staphylococcus aureus• Rotavirus• Norwalk virus (Noro virus)
Routes of exposure to enteric pathogens
• Fecal contamination (human/animal)
–Food
–Water
–Fomites (doorknobs, telephones)
–Direct contact
Non-traditional pets
Pest animals
Population at risk
Occupational risk
STAPHYLOCOCCAL FOOD POISONING
• S. aureus survives 30 min at 60o C (140o F)
• High salt concentration• Skin and nasal mucosa• Facultative anaerobes
-Coagulase positive
STAPHYLOCOCCAL FOOD POISONING
(cont.)• Temperature abuse
–Food let to cool slowly
–Organisms grow producing toxin
STAPHYLOCOCCAL FOOD POISONING
(cont.)• High risk foods
–Custards
–Cream pies
–Ham
STAPHYLOCOCCAL FOOD POISONING (cont.)
• Toxin affects brain’s vomiting reflex
• Abdominal cramps• Diarrhea
SALMONELLOSIS
Salmonella spp.
• Gram negative rods• Facultative anaerobe• 2000 serovars
SALMONELLOSIS (cont.)
• S. dublin• S. enteritidis• S. typhimurium• S. cholerasuis
SALMONELLOSIS (cont.)
• Domestic animals
–Poultry
–Swine
–Cattle
–Dogs and cats
SALMONELLOSIS (cont.)
• Wild animals
–Rodents
–reptiles
–Terrapins (turtles)
SALMONELLOSIS (cont.)
• Incubation of 12 - 36 h• Intestinal mucosa• Lymphatic and cardiovascular
systems
SALMONELLOSIS (cont.)
• Fever• Nausea• Abdominal pain• Cramps• Diarrhea
SALMONELLOSIS (cont.)
• Mortality among infants and the elderly
• Many shed Salmonella for 6 months
• Many animals are chronic carriers
SALMONELLOSIS (cont.)
• Treatment
–Rehydration
–Antibiotics prolong carrier state and increase resistance
TYPHOID FEVER
• Salmonella typhi
–Rare in animals!• Incubation
–2 weeks
TYPHOID FEVER (cont.)
• High fever (104o F)• Continual headache• Constipation more common
than diarrhea• 10% fatality rate
TYPHOID FEVER (cont.)• Many recovered patients become
carriers (Typhoid Mary)• Obligatory case report in most
states and countries• Lifelong immunity
TYPHOID FEVER (cont.)• Treatment
–Cephalosporins
–Chloramphenicol
–Amoxillin
Shigellosis
SHIGELLOSIS (Bacillary dysentery)
• Shigella spp.• Gram negative facultative anaerobic
rod• Only infects humans• Low infectious dose
–Resistant to low stomach pH
SHIGELLOSIS (cont.)• S. sonnei
– Most common in the USA– Least severe
• S. dysenteriae –Uncommon in the USA –Most severe
SHIGELLOSIS (cont.)• Shiga toxin
–Inhibits protein synthesis
–Diarrhea with blood and mucus (dysentery)
SHIGELLOSIS (cont.)• 20,000- 25,000 cases/year• 5 to 15 deaths• Treatment
–Rehydration
–Fluoroquinolones (severe cases)
Cholera
CHOLERA• Vibrio cholerae• Aquatic organism• Gram-negative rod • Non-invasive
–toxin producing
Cholera epidemicSouth America1991-1994• 1 million cases• 9,600 deaths
CHOLERA (cont.)• Enterotoxin• Rice-water stools• 20 liters of liquid lost/day• Occasional outbreaks in Gulf coast
(seafood)
CHOLERA (cont.)• 50% mortality if untreated• 1% mortality if treated
–Rehydration
–Tetracycline
Vibrio gastroenteritis• Vibrio parahaemolyticus• Salt water estuaries• Resembles cholera• Often foodborne (seafood)
E. coli
Escherichia coli gastroenteritis
• Enterotoxigenic E. coli• Enteroinvasive E. coli• Enterohemorrhagic E. coli
Enterotoxigenic E. coli
• Specialized fimbriae
–Attachment• Not invasive• Toxins• Severe diarrhea
Enteroinvasive E. coli• Specialized fimbriae
–Attachment• Toxins (cholera-like)• Traveler’s diarrhea (?) • Penetrate intestinal lining
–Shigellosis-like dysentery
Enterohemorrhagic E. coli• O157:H7 strain• Foodborne (hamburgers, milk,
apple cider)• Verotoxins (colon bleeding)
Enterohemorrhagic E. coli (cont.)
• Cattle carrier• Hemolytic uremic syndrome
–Blood in urine
–Kidney failure
Campylobacter jejuni gastroenteritis
• Gram-negative microaerophilic spirally curved rods
• Common in (healthy) domestic animals
–May be shed in milk• Small infectious dose• Dysentery
Yersinia spp. gastroenteritis
• Common in domestic animals• Grows at refrigeration temperature• Acute pain
Clostridium perfringens gastroenteritis
• Gram-positive, spore-forming anaerobic rod
• Contaminated-cooked meat• Temperature abuse• Mild diarrhea
Bacillus cereus gastroenteritis
• Gram-positive, spore-forming anaerobic rod
• Common in soil and vegetation• Gastroenteritis is similar to Cl.
perfringens
VIRAL GASTROENTERITIS
ROTAVIRUS• Most common viral gastroenteritis• 1,000,000 cases/year (USA)• 100 deaths/hour• (developing countries)
NORWALK VIRUS• Common among adults• More resistant to chlorine than
other viruses• No animal models or cell culture
available
