USMLE PRACTICE QUESTION OF THE WEEK

Question for January 23, 2026

A 54-year-old man with type 2 diabetes is hospitalized for foot ulcer infection. He receives vancomycin and piperacillin-tazobactam. On day 5, he develops fever, abdominal pain, and watery diarrhea. Exam shows diffuse abdominal tenderness without rebound. WBC count is 21,000/µL. CT abdomen reveals colonic wall thickening. Stool assay for toxins is positive.

Which of the following is the most appropriate next step in management?

A. IV metronidazole

B. Oral vancomycin

C. Oral fidaxomicin

D. Discontinue antibiotics only

E. Probiotics

Get Detailed Explanation

Correct Answer:

B. Oral vancomycin

Correct Answer Explanation:

This patient has severe Clostridioides difficile colitis (WBC >15,000, abdominal pain, colonic thickening). Oral vancomycin (or fidaxomicin) is first-line. IV metronidazole is used if ileus prevents oral absorption. Discontinuing antibiotics alone is insufficient. Probiotics have no proven role in acute treatment.

Further Insight:

Risk: broad-spectrum antibiotics, especially clindamycin, cephalosporins, fluoroquinolones.
Fulminant disease may require colectomy.