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Life-threatening Clostridioides difficile infection with partial ileus — MRCEM SBA MCQ

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HardInfection and sepsisLife-threatening Clostridioides difficile infection with partial ileusMRCEM SBA

A 72-year-old woman attends the emergency department after four days of profuse diarrhoea following a course of co-amoxiclav. A stool sample taken yesterday is positive for Clostridioides difficile toxin. She has passed no stool for 12 hours and now has a distended abdomen; CT shows colitis and partial ileus without perforation. Her blood pressure is 84/50 mmHg despite initial intravenous fluid resuscitation. She is alert and can take and retain oral medicines. Critical care, surgical and microbiology reviews are being arranged urgently. Which initial C. difficile antimicrobial regimen is most appropriate?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: E — Vancomycin 500 mg orally four times daily plus metronidazole 500 mg intravenously three times daily.

The positive stool toxin test establishes C. difficile infection in a patient with compatible symptoms. The subsequent cessation of diarrhoea is not reassuring: abdominal distension and CT-confirmed partial ileus, together with persistent hypotension, indicate **life-threatening infection**. NICE advises urgent specialist input, potentially including surgery; specialists may initially offer oral vancomycin 500 mg four times daily **with intravenous** metronidazole 500 mg three times daily. Critical care assessment and ongoing resuscitation are appropriate alongside treatment. If ileus compromises delivery of oral treatment, specialists may consider rectal vancomycin. ([nice.org.uk](https://www.nice.org.uk/guidance/ng199/chapter/Recommendations)) A includes intravenous metronidazole but uses the vancomycin dose recommended for a first episode that is not life-threatening. B might appeal because fidaxomicin treats C. difficile, but it is not NICE’s suggested initial regimen for life-threatening disease. C gives the higher vancomycin dose but changes metronidazole to the oral route; the suggested combination uses intravenous metronidazole. D combines two enteral agents instead of using the recommended intravenous component. The patient’s ability to retain oral medicines permits the oral vancomycin route now, while partial ileus warrants specialist reassessment of drug delivery. ([nice.org.uk](https://www.nice.org.uk/guidance/ng199/chapter/Recommendations))

Reference: NICE NG199: Clostridioides difficile infection: antimicrobial prescribing — Recommendations (23 July 2021) — https://www.nice.org.uk/guidance/ng199/chapter/Recommendations NICE NG199: Clostridioides difficile infection: antimicrobial prescribing — Recommendations 1.1.7 and table 1 (23 July 2021) — https://www.nice.org.uk/guidance/ng199/chapter/Recommendations NICE NG199: Rationale and impact — Treating suspected or confirmed C. difficile infection (23 July 2021) — https://www.nice.org.uk/guidance/NG199/chapter/rationale-and-impact