If a patient with C. difficile infection cannot discontinue the offending antibiotic, what is the recommended approach?

• A. Stop the antibiotic and give metronidazole
• B. Continue the offending antibiotic and give metronidazole
• C. Stop all antibiotics and observe
• D. Switch to a different antibiotic

Answer: (B)

When C. difficile infection occurs but the offending antibiotic cannot be stopped, the plan is to treat the CDI while continuing the necessary antimicrobial therapy. The goal is to suppress toxin-producing C. difficile while not compromising essential treatment for the patient’s primary condition. Metronidazole has activity against C. difficile and has historically been used for mild-to-moderate CDI, helping to reduce symptoms and toxin activity without requiring interruption of the essential antibiotic. If the antibiotic could be stopped, that is often preferred, but when it cannot, continuing it and adding targeted anti-C. difficile therapy is the practical approach.

Stopping all antibiotics or switching to another antibiotic without addressing the CDI would not control the infection, and stopping the offending agent contradicts the scenario’s constraint.