Treatment for pseudomembranous colitis due to C. difficile is which of the following?

Treatment for pseudomembranous colitis due to C. difficile is which of the following?

• A. IV vancomycin
• B. Metronidazole IV
• C. Oral vancomycin
• D. Oral amoxicillin

Answer: (C)

Key idea: CDI infection is best treated with an antibiotic that stays in the gut lumen to eradicate C. difficile where the toxin acts. Oral vancomycin achieves very high concentrations in the colon because it remains largely in the GI tract after administration, so it effectively suppresses the pathogen at the site of infection without relying on systemic levels. IV vancomycin, on the other hand, is poorly delivered to the colon and won’t reach therapeutic concentrations where the bacteria reside, making it ineffective for this colitis. Metronidazole has historically been used but is no longer preferred for initial therapy due to lower efficacy in many cases, though it can be considered in specific situations. Amoxicillin is not a treatment for C. difficile and can worsen antibiotic-associated diarrhea by further disrupting normal gut flora. Therefore, oral vancomycin is the best choice for treating pseudomembranous colitis caused by C. difficile.

Key idea: CDI infection is best treated with an antibiotic that stays in the gut lumen to eradicate C. difficile where the toxin acts. Oral vancomycin achieves very high concentrations in the colon because it remains largely in the GI tract after administration, so it effectively suppresses the pathogen at the site of infection without relying on systemic levels. IV vancomycin, on the other hand, is poorly delivered to the colon and won’t reach therapeutic concentrations where the bacteria reside, making it ineffective for this colitis. Metronidazole has historically been used but is no longer preferred for initial therapy due to lower efficacy in many cases, though it can be considered in specific situations. Amoxicillin is not a treatment for C. difficile and can worsen antibiotic-associated diarrhea by further disrupting normal gut flora. Therefore, oral vancomycin is the best choice for treating pseudomembranous colitis caused by C. difficile.