Ann IM 1998;129:221

Cause:Clostridium botulinum(types A, B, E are the most common human pathogens)

Pathophys:

Exotoxin is heat-labile, extremely toxic (<1 lb could kill the world); inhibits transmitter release at all cholinergic endings

In infants and occasionally in adults with impaired gastric acid, can generate toxin in human gi tract

Heat-resistant spores contaminate:

• Canned foods or opened cans kept for days unrefridgerated (Ann IM 1996;125:558) leading to bacterial proliferation of exotoxin, which then is ingested without further heating, eg, homemade salsa, relish, canned vegetables or meats, garlic in oil, etc
• Wounds where bacterial proliferation and exotoxin production (80% type A, 20% type B)

Spores common in dirt and dust

Sx:Incubation period of 12 h to several days; mild gi sx; descending paralysis of motor and autonomic nerves starting w cranial nerves: double vision, dysphagia, dysarthria; upper respiratory tract paralysis with trouble breathing and swallowing

Si: "Myasthenia gravis that doesn't respond to edrophonium (Tensilon)," though some may a little; flaccid paralysis

Pts can survive and recover with respirator and other supportive care for weeks to months

r/o myasthenia, Guillain-Barré, diphtheria, CVA, Eaton-Lambert syndrome; intoxication w organophosphates, CO, paralytic shellfish toxins

Lab:

Bact: Smear of food shows gram-pos bacilli; food and/or stool culture grows obligate anaerobe; extract kills mice

CSF:Normal

Noninv:EMG shows low-amplitude response to nerve stimulation increased by 50/s repetitive stimulation, 15-40% false neg

Rx:

Preventively heat all canned food prior to serving; immunization impractical on widespread scale

of disease: passive immunization with polyvalent horse antitoxin in adults helps before severe sx set in, available from CDC, but serum sickness precludes use in infants; type-specific if possible. Debride wounds. Gastric lavage if food recently ingested. Supportive care, eg, respirator, etc × weeks to months usually successful

in infants w large bowel botulism, human botulism immune globulin iv shortens course (Nejm 2006;354:462)