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Autism screening — USMLE Step 3 MCQ

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HardPediatrics (Well-child / Chronic Management)Autism screeningUSMLE Step 3

A 73-year-old nursing-home resident develops profuse diarrhea after cefepime. Stool testing confirms toxigenic Clostridioides difficile. Despite fluid resuscitation, blood pressure is 84/48 mm Hg; the abdomen is distended, lactate is 4.8 mmol/L, and CT shows pancolitis with ileus but no perforation. What is the best initial antimicrobial regimen while obtaining urgent surgical consultation?

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Correct answer: C — Give enteral vancomycin 500 mg four times daily plus IV metronidazole 500 mg every 8 hours and rectal vancomycin 500 mg in 100 mL saline every 6 hours

The best answer is “Give enteral vancomycin 500 mg four times daily plus IV metronidazole 500 mg every 8 hours and rectal vancomycin 500 mg in 100 mL saline every 6 hours”. Shock and ileus define fulminant disease. Treatment is enteral vancomycin 500 mg four times daily plus IV metronidazole 500 mg every 8 hours; add vancomycin 500 mg in approximately 100 mL saline rectally every 6 hours because ileus can impede colonic delivery. Fulminant C. difficile infection with shock or ileus is treated with high-dose enteral vancomycin plus intravenous metronidazole; rectal vancomycin is added when ileus limits colonic drug delivery.

Reference: IDSA/SHEA: Clostridioides difficile Infection Guideline: https://www.idsociety.org/practice-guideline/clostridium-difficile/