USMLE Step 2 Antibiotics and Treatments Practice Exam 2025 - Free Practice Questions and Study Guide

Clostridium perfringens is a gram-positive anaerobic bacterium commonly associated with gas gangrene and food poisoning. The preferred treatment for infections caused by this organism generally involves the use of antibiotics that are effective against anaerobic bacteria and that can also target the toxin-producing capabilities of C. perfringens.

Clindamycin is particularly effective as it acts against anaerobic bacteria and also inhibits toxin production, providing dual benefits in the treatment of C. perfringens infections. Meanwhile, penicillin is employed to target the bacterial cell wall, effectively aiding in the elimination of the organism. The combination of these two drugs is often used to enhance efficacy and reduce morbidity associated with C. perfringens infections.

In contrast, other antibiotic combinations mentioned in the options may not provide the necessary activity or are not the standard of care. For instance, amphotericin is primarily an antifungal, making it unsuitable for treating C. perfringens. The pairing of ceftriaxone and rifampin does not effectively address the specific needs of this anaerobic infection. Similarly, doxycycline and vancomycin target different pathogens and may not deliver the necessary coverage for C. perfringens. Therefore, the best combination