Clostridium botulinum (anaerobic)

Question 1

Disease

Answer 1

Botulism

Question 2

Transmission

Answer 2

• Spores in soil, contaminate vegetables & meats.
• Foods canned or vacuum-packed without adequate sterilization, spores survive & germinate in anaerobic environment.
• Toxin produced in canned food & ingested preformed.
• Highest-risk foods:
  (1) alkaline vegetables (green beans, peppers, & mushrooms)
  (2) smoked fish.
• heat-labile-> inactivated by boiling minutes.

Question 3

Pathogenesis: botulinum toxin

Answer 3

• absorbed from gut & carried blood to peripheral nerve synapses-> blocks acetylcholine release.
• protease cleaves proteins involved in acetylcholine release.
• polypeptide encoded by lysogenic phage.
• 8 immunologic types of toxin; types A, B, and E most common in human illness.

Botox-> commercial preparation of exotoxin A-> remove wrinkles on face.

Minute amounts of toxin effective in treatment of certain spasmodic
muscle disorders (writer’s cramp & blepharospasm).

Question 4

Clinical Findings

Answer 4

• Descending weakness & paralysis, diplopia,
  dysphagia, & respiratory muscle failure.
• No fever present.

2 special clinical forms:

(1) wound botulism
- spores contaminate wound, germinate, & produce toxin at site

(2) infant botulism
- organisms grow in gut & produce toxin.
- Ingestion of honey-> Affected infants develop
weakness or paralysis & need respiratory support
but recover spontaneously.

Question 5

Laboratory Diagnosis

Answer 5

• not cultured.
• toxin demonstrable in uneaten food & patient’s
  serum by mouse protection tests.
• Mice inoculated with sample of clinical specimen & die unless protected by antitoxin.

Enzyme-linked immunoassay (EIA) tests &(PCR) used.

Question 6

Treatment

Answer 6

• heptavalent antitoxin containing all 7 types (A to G) preferred to trivalent antitoxin with types A,
  B, E.

Respiratory support.

Antitoxin made in horses & serum sickness occur.

A bivalent antitoxin (A & B) purified from plasma of humans immunized with botulinum toxoid available
for treatment of infant botulism.

Question 7

Prevention

Answer 7

• Proper sterilization of all canned & vacuum-packed
  foods
• Adequately cooked food
  -> inactivate toxin.
  Swollen cans->clostridial
  proteolytic enzymes form gas.