C. difficile Infection

Your patient on day 8 of broad-spectrum antibiotics develops profuse watery diarrhea — and you reach for the alcohol-based hand sanitizer. You just made the one mistake that keeps this organism circulating.

Clostridioides difficile is an anaerobic, spore-forming bacterium and the leading cause of healthcare-associated infectious diarrhea. Spores persist on surfaces for months and resist alcohol-based sanitizers and routine cleaning agents. Risk factors include antibiotic use (fluoroquinolones, clindamycin, and broad-spectrum cephalosporins are highest risk), age over 65, proton pump inhibitor use, prolonged hospitalization, and immunosuppression. Clinical presentation includes watery diarrhea (≥3 unformed stools in 24 hours), fever, abdominal pain and distension, leukocytosis (WBC sometimes >20,000), and hypoalbuminemia. Fulminant disease can progress to toxic megacolon, bowel perforation, and septic shock. Diagnosis is by stool testing — PCR for toxin gene or enzyme immunoassay for toxins A and B. Critical rule: do NOT test formed stool and do NOT repeat testing during the same episode to confirm cure. First-line treatment per current IDSA/SHEA guidance: fidaxomicin 200 mg twice daily for 10 days is preferred when available; oral vancomycin 125 mg four times daily for 10 days is an acceptable alternative. Metronidazole is no longer preferred except when recommended agents are unavailable in nonsevere disease. For first recurrence, fidaxomicin is preferred. For multiple recurrences, fecal microbiota transplantation (FMT) is effective. Infection prevention: contact precautions with gown and gloves, hand hygiene with SOAP AND WATER (alcohol-based hand rub does NOT kill C. diff spores), private room preferred, bleach-based environmental disinfection (1:10 sodium hypochlorite solution), and discontinue the inciting antibiotic when possible.

Key Distinctions

The #1 tested distinction: alcohol-based hand sanitizer is ineffective against C. diff spores — soap and water with mechanical friction is required. Students often select metronidazole as first-line treatment; current guidelines prefer fidaxomicin, with oral vancomycin as an acceptable alternative. Do not confuse C. diff colitis with other causes of antibiotic-associated diarrhea — C. diff requires specific testing and contact precautions, while simple antibiotic diarrhea does not. Testing formed stool or repeating testing as a test of cure are common errors.

Clinical Pearl

C. diff and soap — both need water. Alcohol gel is useless against spores.