C. difficile should be ruled out in which patients?

C. difficile should be ruled out in which patients?

• A. Patients with diarrhea who have recently received antibiotic therapy
• B. Patients with constipation
• C. Patients with diarrhea and dehydration
• D. All patients with diarrhea

Answer: (A)

The key idea is that antibiotic exposure greatly increases the likelihood of a C. difficile infection. When the gut microbiota is disrupted by antibiotics, C. difficile can overgrow and release toxins that cause diarrhea and inflammation. Therefore, in a patient who develops diarrhea after recent antibiotic therapy, ruling out C. difficile is the most appropriate and prudent step to promptly diagnose and treat if needed and to implement appropriate precautions. Constipation does not align with C. difficile symptoms, and while diarrhea with dehydration can occur with CDI, the strongest and most actionable risk signal here is recent antibiotic use. Testing all patients with diarrhea isn’t typically indicated—testing is guided by pre-test probability, with antibiotic exposure being the primary driver.

The key idea is that antibiotic exposure greatly increases the likelihood of a C. difficile infection. When the gut microbiota is disrupted by antibiotics, C. difficile can overgrow and release toxins that cause diarrhea and inflammation. Therefore, in a patient who develops diarrhea after recent antibiotic therapy, ruling out C. difficile is the most appropriate and prudent step to promptly diagnose and treat if needed and to implement appropriate precautions.

Constipation does not align with C. difficile symptoms, and while diarrhea with dehydration can occur with CDI, the strongest and most actionable risk signal here is recent antibiotic use. Testing all patients with diarrhea isn’t typically indicated—testing is guided by pre-test probability, with antibiotic exposure being the primary driver.