Clostridium species

MICROBIOLOGY

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.

Clostridia + Clostridial toxins*
Clostridia	Toxin	Disease
Gastrointestinal tract
C. perfringens	Enterotoxin	Food intoxication, diarrhea, sudden infant death
C. perfringens	Beta toxin	Necrotic enteritis
C. difficile	Ted A + Ted B	Antibiotic-associated diarrhea + colitis
C. septicum	Alpha	Intestinal myonecrosis
C. botulinum	BoNT/A, B, E	Human botulism
Wound-related diseases
C. perfringens	alfa toxin	Gangrene, Puerperal sepsis
C. sordellii	Tcsl, Tcstl	Gangrene
C. tetani	TeNT	Tetanus
C. novyi	Alpha-novyi	Gangrene
C. botulinum	BoNT/A + B	Wound botulism
* Adapted from Popoff MR, Bouvel P; Future Microbio 2009; 4: 1021[9]
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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Last updated: November 7, 2019