Introduction

•  Botulism is caused by the most potent neurotoxins known.

  • Neurotoxins are produced and liberated by Clostridium botulinum.

• C. botulinum, ubiquitously found in soil and marine environments, is a group of gram positive anerobes that form spores.

• Eight distinct toxins have been characterized, all but one being neurotoxic.

• Botulinum neurotoxin affects cholinergic nerve terminals:

  •   Postganglionic parasympatetic endings

  •   Neuromuscular junctions

  •   Peripheral ganglia

• CNS is not involved.

• Botulinum neurotoxin prevents acetylcholine release:

  1.    Binds presynaptically

  2.    Internalized in vesicular form

  3.    Released into the cytoplasm

  4.    The toxin(s), zinc endopeptidases) causes proteolysis of components of the neuroexocytosis system.

Clinical presentations

•  Descending paralysis which can lead to respiratory failure

•  Onset of symptoms is referable to cranial nerve involvement:

  •   Diplopia

  •   Dysarthria/dysphagia

Treatment

• Supportive

• For food-borne illness, trivalent (types A,B and E) equine antitoxin

• Antibiotic treatment is of unproven value.

Abrutyn, E. Botulism . In Harrison's Principles of Internal Medicine 14th edition, (Isselbacher, K.J., Braunwald, E., Wilson, J.D., Martin, J.B., Fauci, A.S. and Kasper, D.L., eds) McGraw-Hill, Inc (Health Professions Division), 1998, p. 904-905