Which antibiotic is added when prosthetic valves are present in infective endocarditis?

Which antibiotic is added when prosthetic valves are present in infective endocarditis?

• A. Rifampin
• B. Vancomycin alone
• C. Linezolid
• D. Clarithromycin

Answer: (A)

Prosthetic valve endocarditis involves bacteria growing as a biofilm on the artificial valve, which makes them much harder to eradicate with standard antibiotics. Rifampin is added because it penetrates biofilms effectively and works well against staphylococci in these biofilm communities. To prevent rapid resistance, it must always be used in combination with another IV agent (such as vancomycin or a beta-lactam, chosen based on susceptibility). The other antibiotics listed don’t offer the same reliable biofilm penetration or adjunctive effect in prosthetic valve infections, so rifampin is the best add-on in this setting.

Prosthetic valve endocarditis involves bacteria growing as a biofilm on the artificial valve, which makes them much harder to eradicate with standard antibiotics. Rifampin is added because it penetrates biofilms effectively and works well against staphylococci in these biofilm communities. To prevent rapid resistance, it must always be used in combination with another IV agent (such as vancomycin or a beta-lactam, chosen based on susceptibility). The other antibiotics listed don’t offer the same reliable biofilm penetration or adjunctive effect in prosthetic valve infections, so rifampin is the best add-on in this setting.