Which antibiotic is commonly used to treat suspected MRSA infective endocarditis?

Which antibiotic is commonly used to treat suspected MRSA infective endocarditis?

• A. Ceftriaxone
• B. Amoxicillin
• C. Penicillin G
• D. Vancomycin

Answer: (D)

The key concept is obtaining reliable activity against MRSA in endocarditis. MRSA is resistant to beta-lactams such as ceftriaxone, amoxicillin, and penicillin G, so those drugs won’t reliably treat MRSA infections. Vancomycin, on the other hand, targets the bacterial cell wall in a way that MRSA remains susceptible to, making it the standard IV therapy for suspected MRSA endocarditis. It provides proven, bactericidal activity in the heart valves while susceptibility results are pending. In some cases alternatives like daptomycin or linezolid are used, but vancomycin is the classic choice for suspected MRSA endocarditis.

The key concept is obtaining reliable activity against MRSA in endocarditis. MRSA is resistant to beta-lactams such as ceftriaxone, amoxicillin, and penicillin G, so those drugs won’t reliably treat MRSA infections. Vancomycin, on the other hand, targets the bacterial cell wall in a way that MRSA remains susceptible to, making it the standard IV therapy for suspected MRSA endocarditis. It provides proven, bactericidal activity in the heart valves while susceptibility results are pending. In some cases alternatives like daptomycin or linezolid are used, but vancomycin is the classic choice for suspected MRSA endocarditis.