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First CDI Recurrence — RACP Adult Medicine MCQ

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ModerateInfectious DiseasesFirst CDI RecurrenceRACP Adult Medicine

A 60-year-old man presents with acute onset watery diarrhoea and abdominal cramps. He recently completed a course of antibiotics. Stool PCR is positive for Clostridioides difficile toxin genes. He has had one prior CDI episode 3 months ago. What is the recommended treatment for a first recurrence?

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Correct answer: B — Oral vancomycin tapered and pulsed regimen

For the first recurrence of CDI, a vancomycin tapered and pulsed regimen is recommended: vancomycin 125 mg QID for 10–14 days, then 125 mg BD for 7 days, then 125 mg daily for 7 days, then 125 mg every 2–3 days for 2–4 weeks. Fidaxomicin (which has lower recurrence rates) is an alternative for first recurrence. FMT is reserved for the second or subsequent recurrence. Standard-dose vancomycin without taper has a high recurrence rate (~25–30%). Metronidazole is no longer first-line for any CDI episode.

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