Rifampin may be used in combination with other antibiotics to treat resistant infections caused by which organism?

• A. Fungal
• B. Gram negative
• C. Viral
• D. Staphylococcal

Answer: (D)

Rifampin is especially used with other antibiotics to treat resistant staphylococcal infections because of its ability to penetrate biofilms and intracellularly, delivering rapid activity against Staphylococcus aureus, including MRSA. However, when rifampin is used alone, the bacteria quickly develop resistance, so it’s combined with another active antibiotic to prevent that resistance and achieve a stronger, synergistic effect. This strategy is particularly important in tough infections like prosthetic joint infections, osteomyelitis, endocarditis, or persistent bacteremia caused by Staphylococcus species.

Rifampin works by inhibiting bacterial RNA polymerase, a mechanism that doesn’t apply to fungi or viruses, which is why it isn’t used for fungal or viral infections. Its use is also not routine for Gram-negative infections, where it’s less reliably effective and resistance can still arise, hence its role is mainly in staphylococcal (often MRSA) scenarios when used in combination with other agents. Be mindful of drug interactions and liver safety, as rifampin induces certain liver enzymes and can affect many other medications.