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Clostridioides difficile infection — MCCQE Part 1 MCQ

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ModerateDiarrheaClostridioides difficile infectionMCCQE Part 1

78-year-old woman recently treated with antibiotics presents with profuse watery diarrhoea and abdominal cramping. She has leukocytosis and a positive stool toxin assay. Which of the following is the most appropriate next step?

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Correct answer: B — Start oral vancomycin or fidaxomicin according to severity and stop unnecessary antibiotics

Start oral vancomycin or fidaxomicin according to severity and stop unnecessary antibiotics is best because recent antibiotics and positive toxin testing make CDI likely. Discharge with reassurance and routine follow-up only is suboptimal because it underestimates acute or progressive risk; Treat symptomatically and defer definitive assessment is suboptimal because symptom control alone does not address the likely underlying diagnosis; Arrange non-urgent outpatient imaging in several months is suboptimal because delayed imaging is unsafe when the presentation has red flags; Start long-term corticosteroids without confirming the diagnosis is suboptimal because empiric steroids can obscure infection, malignancy or other diagnoses. Avoid antimotility agents in severe infectious colitis.

Reference: AMMI Canada CDI guidance