What is the first-line treatment for pseudomembranous colitis?

• A. Oral metronidazole
• B. Oral vancomycin
• C. Intravenous vancomycin
• D. Probiotics

Answer: (B)

The first-line treatment for pseudomembranous colitis, particularly when caused by Clostridium difficile, is oral vancomycin. This antibiotic is specifically effective against C. difficile due to its ability to remain concentrated in the intestine, which is crucial for treating intestinal infections. Oral vancomycin is preferred over other treatments primarily because it has a high efficacy for this infection and a favorable safety profile.

Oral metronidazole may be considered in certain cases, especially in mild infections, but current guidelines emphasize the use of oral vancomycin as the primary treatment, particularly for moderate to severe cases of pseudomembranous colitis. Intravenous vancomycin is not effective for treating C. difficile infections because it does not reach adequate concentrations in the gut when administered via this route. Probiotics may have a role in prevention or adjunct therapy, but they are not established as a primary treatment for the active infection.