USMLE

Clostridium perfringens

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Bacteria - Gram Positive
  1. Staph aureus: Overview
  2. Staph aureus: Presentation
  3. Methicillin-Resistant Staph aureus (MRSA)
  4. Staph saprophyticus
  5. Strep pneumoniae: Overview
  6. Strep pneumoniae: Presentation
  7. Strep viridans
  8. Strep pyogenes: Overview
  9. Strep pyogenes: Presentation
  10. Strep agalactiae
  11. Strep bovis
  12. Enterococcus
  13. Bacillus anthracis
  14. Bacillus cereus
  15. Clostridium tetani
  16. Clostridium perfringens
  17. Clostridium botulinum
  18. Clostridium difficile
  19. Corynebacterium diphtheriae
  20. Listeria monocytogenes
  21. Nocardia
  22. Actinomyces

Clostridium perfringens 

  • Characteristics
    • Common to all bacteria in Clostridia family
    • Gram + rods
    • Obligate anaerobic
    • Spore-forming
      • Spores live in soil
    • Double zone of beta-hemolysis on blood agar
  • Produces lecithinase (an exotoxin)
    • Also known as phospholipase C or alpha-toxin
    • Cleaves membrane lipid lecithins (phospholipase) to cause cell lysis (e.g. hemolysis), tissue necrosis, and edema
    • increases platelet aggregation and adherence molecule expression on WBCs and endothelial cells, resulting in blood vessel occlusion and ischemia in downstream tissues
  • Exposure
    • Penetrating injury
      • Spores enter via contaminated objects (e.g. soil, surgery)
  • Presentation
    • myonecrosis (gas gangrene)
      • Rapid developing necrotizing fasciitis in skin and soft tissue, mediated by lecithinase
      • Tissue damage and necrosis with gas that can be felt on examination (crepitus)
      • Purple-black discoloration of affected limb 
    • Late-onset food poisoning
      • Caused by ingestion of large amounts of spores producing heat-labile enterotoxin
      • Transient watery diarrhea occurs in 10-12 hours after ingestion
        • Occurs slowly since toxin is not pre-formed
    • Hemolysis
  • Treatment
    • Immediate surgical debridement for gas gangrene
      • Surgical emergency, poor prognosis even with treatment
    • Antibiotics
      • Penicillin and clindamycin