Clostridium botulinum

Clostridium botulinum is one species of the genus Clostridia. It is a Gram-positive, motile rod. Morphologically, it possesses sub-terminal spores. It only grows in an anaerobic environment where it produces irregular colonies on normal media.

Its natural habitat is the soil, but it can contaminate vegetables, fruit and other foods.

There are seven types of C. botulinum - A,B,C,D,E, F and G - each produces an antigenically different toxin.

• seven different strains of Clostridium have been described (designated A, B, C (1 and 2), D, E, F and G), and each produces a distinct neurotoxin identified by the corresponding letter of the bacterial strain producing it, so, there are 7 distinct neurotoxins (BTX-A, -B, -C, -D, -E, -F, -G) (1)
  • humans can be affected by the toxins of 5 strains (A, B, E, F and G) and are not affected by the toxins of strains C and D
  • all 7 toxins may potentially cause botulism in humans given a high enough exposure (1)
  • alll 7 neurotoxins are structurally similar but immunologically distinct
    • there is some serum cross-reactivity among the serotypes because they share some sequence homology with one another as well as with tetanus toxin

Reference:

• 1) Majid OW. Clinical use of botulinum toxins in oral and maxillofacial surgery. Int J Oral Maxillofac Surg. 2010 Mar;39(3):197-207. Epub 2009 Dec 2