Welcome to the Infant Botulism Treatment and Prevention Program

Microbiology of Clostridium botulinum

Clostridium botulinum is a spore-forming, obligately anaerobic, Gram-positive bacillus that produces a heat-labile neurotoxin. This organism is divided into four physiological groups that produce eight antigenically distinct toxin types, which are classified as botulinum toxin types A-H. Botulinum toxin is the most potent toxin known. The mode of action of botulinum toxin is to cleave key proteins that are necessary for the release of acetylcholine into the neuromuscular junction. The end result of the toxemia is a descending, bilateral, symmetric, flaccid paralysis. Hallmark clinical features of botulism include: ptosis (droopy eyelids), diplopia (double vision), difficulty swallowing, diminished reflexes and hypotonia. Complete paralysis of the airway and respiratory muscles may lead to cessation of breathing and death.

Two other clostridial species have acquired the gene to produce botulinum toxin. Very rare strains of C. butyricum and C. baratii have been found to produce botulinum toxin type E and toxin type F, respectively. Most of these rare toxigenic C. butyricum and C. baratii strains were discovered because they caused intestinal (infant) botulism.