Kertaus klostridiumlajeista: Clostridium ( Firmicutes, anaerobisia itiöitä muodostavia, toksiineja tuottavia grampositiivisia sauvoja)

 

Johns Hopkins ABX GuidePathogensBacteria

Clostridium species

Paul G. Auwaerter, M.D.

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)
    • Clostridia that produces human pathogenic neurotoxins types A, B, E, F and G.
      • Known botulinum toxin-producing strains include:
        • C. botulinum
        • C. butyricum
        • C. baratii
      • Also, see Clostridium botulinum
  • Colitis (C. difficile)
  • Spore-forming anaerobe, Gram-positive bacillus [Fig 1].
    
    • Found in human and animal feces, also in water and soils.
    • Reclassified as molecular sequencing suggests that the organism should be in the Peptostreptococcaceae family and termed Peptoclostridium.
      • Clostridioides difficile name selected to differentiate from Clostridiaspp., which are not related but allowing for less clinical confusion moving from the long-standing terminology of Clostridium difficile[12].
  • Produces toxins A and B that cause colitis in humans.
  • Occasionally grown in anaerobic cultures, rarely a cause of infection other than colitis.
  • Tetanus (C. tetani)
    • Clostridium tetani is a Gram-positive bacillus, obligate anaerobe.
      • If culture enters the endospore stage, it may have classic tennis racquet morphology [Fig 1].
    • Spores are widespread in soil and animal feces.
    • The rod-shaped appearance on a Gram stain is often likened to drumsticks or tennis rackets.
    • Toxin, tetanospasmin, causes tetanus: unopposed muscle spasm and contraction due to interference of toxin with neurotransmitters (including GABA and glycine).
  • Septic abortion (C. sordellii)
  • Gas gangrene (C. perfringens, C. novyi, C. septicum, C. sordellii, C. histolyticum)

    Common clostridial species causing gas gangrene:

  • Clostridium perfringens
    • Most commonly identified organism.
    • Produces > 20 exotoxins, including lethal Alpha and Beta toxins that cause necrosis and hemolysis.
  • Clostridium novyi  
  • Clostridium septicum  
  • Clostridium histolyticum  
  • Clostridium sordellii (seen with toxic shock after childbirth, users of contaminated heroin injections and patients with malignancy)
    • Review of spontaneous C. sordelli-associated gas gangrene found that known or occult malignancy was seen in 71% of the 94 patients in the literature; overall mortality was 67%[3].
  • 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
	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