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Clostridioides difficile Infection — RACP Adult Medicine MCQ

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EasyGastroenterology & HepatologyClostridioides difficile InfectionRACP Adult Medicine

A 35-year-old man presents with a 3-day history of profuse watery diarrhoea, abdominal cramps, and dehydration. He completed a course of amoxicillin-clavulanate 2 weeks ago. Stool PCR is positive for Clostridioides difficile toxin. What is the recommended first-line treatment for a first episode of non-severe CDI?

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Correct answer: C — Oral vancomycin 125 mg QID for 10 days

For a first episode of non-severe C. difficile infection, the updated eTG Antibiotic guidelines (2025) and IDSA/SHEA guidelines recommend oral vancomycin 125 mg QID for 10 days as first-line therapy. Fidaxomicin is an alternative with lower recurrence rates. Metronidazole is no longer recommended as first-line due to inferior efficacy compared to vancomycin. Faecal microbiota transplantation is reserved for recurrent CDI (≥2 recurrences).

Reference: eTG – 2025 – Antibiotic Guidelines; IDSA/SHEA – 2021 – CDI Guidelines