Clostridium Difficile Infection

Author: Michelle Lin, MD
Updated: 6/24/2011

Clostridium Difficile Infection (CDI)


1st episode, mild-moderate severity

  • Treatment: Metronidazole 500 mg PO TID x 10-14 days

1st episode, severe

  • Serum WBC ≥15k or creatinine > 1.5x baseline
  • Treatment: Vancomycin 125 mg PO QID x 10-14 days

1st episode, severe,complicated

  • Hypotension, shock ileus, or megacolon
  • Treatment: Vancomycin 500 mg QID PO/NG (PR if ileus) PLUS Metronidazole 500 mg IV q8h

First recurrence

  • Same as for 1st episode (because minimal resistance)

Second and more recurrences

  • Treatment: Vancomycin PO in tapered or pulsed regimen. Avoid metronidazole overuse because of neurotoxicity.


Definition of Clostridium difficile infection (CDI)

  • Presence of diarrhea (3 unformed stools in ≤24 hours)
  • Stool test positive for C. difficile or its toxins, or colonoscopic findings of pseudomembranous colitis


  • Accounts for 20-30% of all antibiotic-associated diarrhea
  • Most common cause of infectious diarrhea in healthcare settings


  • Fecal-oral route
  • Median time from exposure to C. difficile to diarrhea symptoms = 2-3 days

Risk factors to develop CDI

  • Age ≥ 65 years
  • Duration of hospitalization
  • Exposure to antibiotics (almost every Abx has been assoc with CDI – not just clindamycin)
    • 96% have received abx within 14 days before diarrhea onset
  • Cancer chemotherapy
  • HIV
  • GI surgery or manipulation of GI tract (i.e. tube feeding)

Clinical presentation

  • Diarrhea may have mucous or occult blood

Recurrence rates


  • Bowel perforation
  • Dehydration
  • Electrolyte imbalance
  • Hypoalbuminemia
  • Hypotension
  • Renal failure
  • SIRS, sepsis
  • Toxic megacolon
  • Death


  • Cohen SH, et al. Clinical practice guidelines for Clostridium difficile infection in adults: 2010 update by SHEA and IDSA. Infect Control Hosp Epidemiol. 2010; 31(5):431-55. [PubMed]
  • Kelly CP, LaMont JT.Clostridium difficile--more difficult than ever.N Engl J Med. 2008 Oct 30;359(18):1932-40. doi: 10.1056/NEJMra0707500. [PubMed]