C. difficile Risk — ORE Part 1 MCQ

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ModeratePharmacology & TherapeuticsC. difficile RiskORE Part 1

Which of the following antibiotics prescribed by dentists has the highest association with Clostridioides difficile infection?

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Correct answer: E — Clindamycin

Explanation lettering: E = shown as A · C = shown as B · D = shown as C · B = shown as D · A = shown as E

Clindamycin (A) is the correct answer. UK NICE guidance and multiple meta-analyses consistently identify clindamycin as carrying the highest risk of C. difficile infection among antibiotics, with a relative risk approximately 2–3 times greater than comparator antibiotics. Amoxicillin (B) is lower-risk; any CDI association is related to volume of use rather than inherent toxicity. Metronidazole (C) is used therapeutically for CDI, not a primary causative agent in this context. Phenoxymethylpenicillin (D) is a narrow-spectrum penicillin with minimal CDI risk. Doxycycline (E) is a tetracycline; evidence explicitly shows tetracyclines are not associated with increased CDI risk. This discriminates candidates who understand evidence-based antibiotic stewardship and UK guidance on prescribing safety.

Reference: NICE Medicines and Prescribing Briefing: Clostridium difficile infection: risk with broad-spectrum antibiotics. https://www.nice.org.uk/advice/esmpb1/chapter/key-points-from-the-evidence (2015)