USMLE

Clostridium difficile

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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 difficile

  • Characteristics
    • Common to all bacteria in Clostridia family
    • Gram + rods
    • Obligate anaerobe
    • Spore-forming
  • Exposure/Risk Factors
    • Antibiotics (esp. broad-spectrum)
      • C. diff is small part of normal gut flora; killing other gut flora by antibiotics creates opportunities for C. diff. to overgrow
      • Commonly associated with clindamycin and ampicillin use
  • Produces 2 toxins
    • Enterotoxin A
      • Disrupts tight junctions of gut to alter fluid secretion in gut
        • Leads to intestinal inflammation (enterotoxic)
        • Causes watery diarrhea
    • Cytotoxin B
      • Disrupts cytoskeleton via actin depolymerization to kill cells
        • Leads to cell death (cytotoxic)
        • Causes colonic epithelial necrosis, inflammation, and fibrin deposition (colitis)
  • Presentation
    • Watery diarrhea
    • Pseudomembranous colitis
      • White/yellow plaques on colonoscopy
      • marked thickening of the colonic wall (accordion sign), irregularity of bowel wall, pericolonic stranding on CT
    • Abdominal pain, weight loss, malaise, dehydration may also be seen
  • Treatment
    • Contact precautions must be used
      • Non-sterile gloves and gown
    • Vancomycin or Metronidazole
      • First-line treatment for isolated C. diff infection
    • Fidaxomicin
      • Used primarily for recurrent infections