Antibacterials (ABX) Practice Exam

Fidaxomicin is used to treat Clostridioides difficile infection, with a key advantage: it lowers the chance of the infection coming back after treatment compared with vancomycin. This drug is a narrow-spectrum macrolide that stays largely in the gut, where C. difficile resides, and it spares much of the normal gut flora. That gut-focused action reduces recurrence, which is a major challenge in CDI management. While vancomycin is effective and commonly used, fidaxomicin’s lower recurrence rate makes it the preferred option in many cases, especially when preventing relapse is a priority. Linezolid isn’t a standard CDI therapy, metronidazole was once used but is now less favored due to inferior outcomes, and vancomycin, though effective, doesn’t typically offer the same reduced recurrence as fidaxomicin.