6. clostridium botulinum
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History of Botulism First discovered in 1793 as foodborne
botulism by Justinus Kerner, a Germanphysician.
Associated with spoiled sausage and aptlynamed botulism after the Latin word forsausage, botulus.
In 1897, Emile von Ermengen was able tocorrelate Clostridium botulinum to thedisease.
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Essential Facts aboutfoodborne botulism It is not an infection, but an intoxication.
The toxin is produced by a specific bacterium.
The toxin is ingested with the food and is notinactivate by the digestive processes.
The organism is relatively resistant to mild
chemical agents, but it is resistant to heat. The toxin is not produced if the concentration
of NaCl is sufficiently high.
Not all species of animals are susceptible.
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Animals Cattle and sheep
Horses
Birds and poultry Mink and ferrets
Uncommon in dogs and pigs
Fairly resistant
No natural cases documented in cats
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Epidemiology In U.S., average 110 cases each year
Approximately 25% food-borne
Approximately 72% infant form Remainder wound form
Case-fatality rate
5-10%
Infective dose- few nanograms
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Epidemiology 1977, Largest botulism outbreak
Michigan - 59 people
Poorly preserved jalapeno peppers Alaska
27% of U.S. foodborne botulism cases
1950-2000
226 cases from 114 outbreaks
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Introduction to the Bacteria Clostridium botulinum
straight to slightly curved, rod-shaped, motile by
peritrichous flagella, and forms oval and subterminal
spores, which usually swell the cell.
Bacteria
Width: 0.52.0 m
Length: 1.622.0 m
Occur naturally in soil, found in gastrointestinal tracts of
animals as well as humans
Survival is dependent on:
Water
Anaerobic conditions
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Neurotoxins Seven different types: A through G
Different types affect different species
All cause flaccid paralysis
Only a few nanograms can cause illness
Binds neuromuscular junctions
Toxin: Destroyed by boiling
Spores: Higher temperatures to be inactivated
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NeurotoxinsNeurotoxin A B C D E F G
Human X X X X
Horses X X
Cattle X X X
Sheep X
Dogs X X
Avian X XMink & Ferret X X X
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Distribution of spores in foodand the environment Type A and B are generally the cause of
outbreaks in more temperate and warmer
zones. Type A spores are found predominantly in
soils.
Type E is common in colder regions in the
northern hemisphere and is mostly
associated in fish and marine mammals.
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Types C and D have been found in marshes
inhabited by birds in localized areas around
the world Type F is found soil.
Type G is found in soil and is difficult to
detect in mixed cultures
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Four physiological groups Group I- proteolytic types A, B and F
Digest meat in cooked meat medium and
casein in milk medium and liquefy gelatine ingelatine medium.
They ferment glucose but not mannose or
sucrose.
Optimal temperature-35-40C, minimal
temperature-10C
Growth is inhibited by 10% NaCl
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Group II- non proteolytic types B, F and all
type E strainsDo not digest casein or meat but they do
liquefy gelatine
Glucose is fermented, as are mannose andsucrose.
Optimal temperature18-25C, minimal
temperature-3.3CGrowth is inhibited by 5% NaCl
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Group IV- type G
Are proteolytic
They slowly digest meat, while gelatine andmeat are rapidly digested.
Glucose, mannose and sucrose are not
fermented.Optimal temperature 37C
Growth is inhibited by 6.5% NaCl
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Growth Gram-positive
Anaerobic
Temperature Optimal: 40C
Minimum:
Proteolytic: 10C
Nonproteolytic: 3.3C
Minimum pH Proteolytic: 4.6 Nonproteolytic: 5.0
Water Activity (aw): 0.94 (+NaCl controls growth)
Redox Potential (E): -350 mV
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Living Conditions Limiting Factors
Low pH (acidic)
In the stomach, BoNTs occur in complexes with other proteins that
protect it from acidity
In the less acidic intestine, the complex disassociates and BoNT is
then absorbed through the epithelial layer and enters the
circulatory system
Nitrite, ascorbic acid, phenolic antioxidants, ascorbates Increase in calcium level counters the effects of BoNTs
A and E
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Botulism Pathogenesis Incubation period
ingestion: unknown
foodborne: 6 hours-8 days
wound: 4-14 days inhalation: (estimated) 24-36 hours
Toxin enters bloodstream from mucosal surface orwound
Binds to peripheral cholinergic nerve endings Inhibits release of acetylcholine, preventing muscles
from contracting
Symmetrical, descending paralysis occurs beginningwith cranial nerves and progressing downward
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Can result from airway obstruction or
paralysis of respiratory muscles
Secondary complications related toprolonged ventilatory support and
intensive care
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Infant Botulism Most common form in U.S.
Spore ingestion
Germinate then toxin released and colonize largeintestine
Infants < 1 year old
94% < 6 months old
Spores from varied sources
Honey, food, dust, corn syrup
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Wound Botulism Occurs when C. botulinum cells or spores
alone or with other microorganisms infect a
deep wound and produce toxin.
Organism enters wound
Develops under anaerobic conditions
From ground-in dirt or gravel
It does not penetrate intact skin
Associated with addicts of black-tar heroin
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Adult infectious botulism In vivo multiplication of the organism and the
subsequent production of toxin.
occurs in wound botulism, but has also beenseen when the multiplication results from
colonization of the intestinal tract.
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Adult Clinical Signs Nausea, vomiting, diarrhea
Double vision
Difficulty speaking or swallowing Descending weakness or paralysis
Shoulders to arms to thighs to calves
Symmetrical flaccid paralysis Respiratory muscle paralysis
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Infant Clinical Signs Constipation
Lethargy
Poor feeding Weak cry
Bulbar palsies
Failure to thrive
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Botulism Transmission Home-canned goods (foodborne)
particularly low-acid foods such as asparagus, beets,
and corn
Honey (ingestion)
can contain C. botulinum spores
not recommended for infants
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Detection of C. botulinum Enrichment
Isolation
Verification
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Treatment Intensive care immediately
Ventilator for respiratory failure
Botulinum antitoxin Derived from equine source
Botulism immune globulin
Infant cases of types A and G
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Human: Prevention Do not feed honey to children 10 minutes
Decontamination Boil suspected food before discarding
Boil or chlorine disinfect utensils used
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Botulism Laboratory Procedures Toxin neutralization mouse bioassay
serum, stool, gastric aspirate, suspect
foods
Isolation ofC. botulinum or toxin
feces, wound, tissue
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Therapeutic use of the toxin It was licensed as Oculinum to treat two eye
conditions-blepharospasm and strabismus.
Treat other medical conditions, such as: Torticollis-contractions of the neck and shoulder
muscles.
Oromandibular dystonia-clenching of the jaw muscles.
Spasmodic dysphonia-resultts in speech that is difficultto understand.
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Why botulinum toxin hasproved to be a good drug? Toxin is highly selective in acting on
cholinergic cells.
Toxin has a long duration of action. Dose of toxin can be individually titrated for
each patient to ensure maximal benefits
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