A 65-year-old patient who had a prosthetic aortic valve replacement 6 months ago develops fever and bacteremia with coagulase-negative staphylococci. What is the standard empiric antibiotic regimen?
Answer and explanation
Correct answer: A. Vancomycin plus gentamicin plus rifampin
- Step 1: Early prosthetic valve endocarditis (within 12 months of valve surgery) is predominantly caused by methicillin-resistant coagulase-negative staphylococci that form biofilms.
- Step 2: Standard guidelines mandate triple therapy with vancomycin, gentamicin for aminoglycoside synergy, and rifampin to penetrate bacterial biofilms on foreign prosthetic material.
Answer
Vancomycin plus gentamicin plus rifampin.
Why not the others: Oral amoxicillin is completely inadequate for prosthetic valve endocarditis. Ceftriaxone monotherapy lacks coverage against methicillin-resistant staphylococci and biofilm production. Penicillin G monotherapy is ineffective against beta-lactamase-producing and methicillin-resistant staphylococci.
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