- Clostridia produce the largest number of toxins of any bacterial class.
- The common source of entry in humans is the gastrointestinal tract or trauma.
- Obligate anaerobic bacteria with unusual features: spore formation, toxin production and normally reside in the environment or the gastrointestinal tract of humans and animals. Dominant form in the human intestinal flora.
- Belongs to phylum Firmicutes, which is the dominant component of the fecal microbiome. Clostridia spp. account for 50% or about 1013/gm stool.
- Species-specific toxin expression:
- Botulism (C. botulinum)
- Colitis (C. difficile)
- Tetanus (C. tetani)
- Septic abortion (C. sordellii)
- Gas gangrene (C. perfringens, C. novyi, C. septicum, C. sordellii, C. histolyticum)
- Clostridial food poisoning (C. perfringens)
- Non-toxigenic strains are often components of mixed infections or bacteremia; pathogenic role often unclear.
Food intoxication, diarrhea, sudden infant death
Ted A + Ted B
Antibiotic-associated diarrhea + colitis
BoNT/A, B, E
Gangrene, Puerperal sepsis
BoNT/A + B
* Adapted from Popoff MR, Bouvel P; Future Microbio 2009; 4: 1021
TeNT - Tetanus toxin; BoNT - Botulinum neurotoxin; TcsH - C. sordellii hemorrhagic toxic; TcsL - C. sordellii lethal toxin; TcdA, alpha-toxin; TedB - Beta toxin
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