A 45-year-old man presents with severe watery diarrhoea (>10 episodes/day), abdominal cramps, and weight loss. He recently completed a course of clindamycin for a dental abscess. Stool GDH and toxin A/B EIA are both positive. CT abdomen shows colonic wall thickening. What is the appropriate treatment for this first severe episode of Clostridioides difficile infection?
- A IV metronidazole alone
- B Oral metronidazole 500 mg three times daily for 10 days
- C Oral vancomycin 125 mg four times daily for 10 days ✓
- D Fidaxomicin as the only acceptable treatment for severe CDI
Correct answer: C. Oral vancomycin 125 mg four times daily for 10 days
Explanation
Current IDSA/SHEA 2021 guidelines classify this as severe CDI (>10 stools/day, leukocytosis, elevated creatinine, colonic wall thickening) and recommend oral vancomycin 125 mg QDS for 10 days as first-line. Oral metronidazole is now reserved for non-severe CDI only, as it is inferior in severe disease. Fidaxomicin is preferred when available to reduce recurrence but is more expensive; oral vancomycin remains the standard where fidaxomicin is unavailable. IV metronidazole is used as adjunct only when colonic ileus prevents oral therapy.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.