Ace the 2025 ROSH GI Challenge – Master the Gut and Own the Exam!

In cases of gastrointestinal symptoms like nausea and diarrhea that develop after hospitalization, especially in the context of recent antibiotic use (such as for pneumonia), one has to consider the possibility of antibiotic-associated diarrhea, which is often caused by Clostridium difficile (C. diff) infection. This is a common complication that occurs when normal intestinal flora are disrupted by antibiotics, allowing pathogenic bacteria like C. difficile to proliferate.

Oral metronidazole is the first-line treatment for mild to moderate C. difficile infections. It works by targeting anaerobic bacteria and is effective in clearing the infection while also helping to alleviate symptoms like diarrhea.

The other options do not address the likely underlying cause of the man's symptoms. For instance, the use of intravenous vancomycin is generally reserved for more severe cases of C. difficile infection or if there is a concern about oral absorption. Oral ciprofloxacin is not indicated in this scenario, as it wouldn't effectively treat a likely C. difficile infection and could potentially exacerbate the issue. Lastly, oral diphenoxylate and atropine are anti-diarrheal medications that would not treat the underlying infection and might worsen the condition by inhibiting the natural elimination of the bacteria from the gut.

Thus, initiating treatment with