6. clostridium botulinum

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  • 7/27/2019 6. Clostridium Botulinum


  • 7/27/2019 6. Clostridium Botulinum


    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


    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


    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


    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.


    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:


    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


    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


    Optimal temperature-35-40C, minimal


    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


    Temperature Optimal: 40C


    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


    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



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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


    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


    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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