First-line therapy for C. difficile infection is which agents?

• A. Oral vancomycin or fidaxomicin; metronidazole for milder disease
• B. Metronidazole for all cases
• C. Oral amoxicillin
• D. Doxycycline

Answer: (A)

Managing C. difficile infection focuses on delivering antibiotics that work well in the gut and minimize recurrence. Oral vancomycin and fidaxomicin are preferred because they achieve high concentrations in the colon where the bacteria reside and have better cure and lower relapse rates than other options. Metronidazole used to be common, but it is less effective, especially for more than mild illness, and has higher relapse rates. Therefore it’s reserved for milder disease or when the preferred agents aren’t available or affordable. In short, start with oral vancomycin or fidaxomicin, and use metronidazole only for milder disease when necessary. Amoxicillin or doxycycline aren’t appropriate first-line treatments for an active C. difficile infection.