Description

• Rare in the U.S., causing <200 cases/yr; however, has significant bioterrorism potential
• Caused by a polypeptide, heat-labile exotoxin produced by Clostridium botulinum:
  • Most potent poison known
• Toxin blocks neuromuscular transmission in cholinergic nerve fibers
• Symptoms occur by inhibition of acetylcholine release from presynaptic nerve membranes:
  • Damage is permanent
  • Recovery is by formation of new synapses through sprouting from the axon
• Onset: 12–72 hr after exposure; may be up to 1 wk after exposure:
  • Death can occur 24 hr after onset of symptoms
• Slow recovery; symptoms often persist for months
• Mortality:
  • Untreated: 60–70%
  • With supportive care: 3–10%
• 3 major types: Foodborne botulism, wound botulism, and infantile botulism (see Pediatric Considerations). Absorbed through mucosal surfaces or nonintact skin
• Foodborne botulism:
  • Occurs by ingestion of preformed toxin; from improperly canned food, improper refrigeration
  • Conditions required for exposure:
    • Food product contaminated with C. botulinum bacilli or spores
    • Proper conditions for germination of spores exist
    • Time and conditions permit production of toxin before eating
    • Food not heated sufficiently to destroy botulism toxin
    • Toxin-containing food ingested by susceptible host
• Wound botulism:
  • Clinical evidence of botulism after trauma with a resultant infected wound and no history suggestive of foodborne illness
  • C. botulinum isolated in about 50% of cases
  • Wounds are usually contaminated with soil
  • Majority of US cases are from IV drug use
• Other types:
  • Adult intestinal toxemia botulism:
    • Seen in adults with functional or structural GI abnormalities, are immunocompromised or with prolonged antibiotic use
    • Predisposes to clostridial colonization
    • May have sporadic or recurrent botulism with no known source and even after immunoglobulin treatment
  • Iatrogenic botulism:
    • Doses found in cosmetic applications are insufficient to cause systemic symptoms
    • No known recent cases from medical use
    • Symptoms would be expected to be classic
  • Inhalation botulism:
    • Aerosolization of toxin may have bioterrorism applications. Last reported naturally occurring case was in 1962 from the disposal of animal remains

• Infantile botulism occurs from the ingestion of C. botulinum spores, which germinate in the gut and produce the toxin
• Accounts for 50–76% of botulism cases
• 90% occur in children <6 mo:
  • Associated with patient or family exposure to soil, dust, or agricultural industry
  • May also be associated with weaning from breast milk, which may alter intestinal flora and increase susceptibility to clostridial infection
• Usually presents with change in stool pattern or constipation, progressing over several days to symptoms of bulbar weakness, then descending flaccid paralysis
• Slower onset is attributed to the toxin being produced locally as opposed to being ingested in 1 dose
• C. botulinum spores found in honey:
  • Honey not recommended for children <1 yr

Etiology

• C. botulinum is a large spore-forming, usually gram-positive, strictly anaerobic bacilli ubiquitous in nature
• Each strain produces antigenically distinct toxins, designated types A–G:
  • Types A, B, E, and rarely F are responsible for most human cases