What is fidaxomicin used for in C. difficile infection and how does it differ from vancomycin?

• A. Fidaxomicin is used for C. difficile infection and is associated with lower recurrence rates compared to vancomycin for some strains
• B. Metronidazole is the preferred therapy for all cases
• C. Vancomycin has lower recurrence rates than fidaxomicin
• D. Rifaximin is the first-line treatment for C. difficile infection

Answer: (A)

Fidaxomicin treats C. difficile infection by acting mainly in the gut with a very narrow spectrum, so it targets C. difficile while sparing most of the normal gut bacteria. This focused action helps preserve the microbiome, which is important because disruption of normal flora contributes to recurrence. Clinically, fidaxomicin and vancomycin have similar initial cure rates, but fidaxomicin lowers the risk of relapse, especially for non-NAP1 strains of C. difficile; for certain strains the advantage is less pronounced. So this choice reflects fidaxomicin’s use in CDI and its lower recurrence tendency compared with vancomycin for some strains.