skip to main content

Enterococcal IE with HLGR — RACP Adult Medicine MCQ

Instant feedback + full explanation. One question, done properly.

HardInfectious DiseasesEnterococcal IE with HLGRRACP Adult Medicine

A 60-year-old man with a prosthetic aortic valve develops a febrile illness. Blood cultures taken over 24 hours grow Enterococcus faecalis. TOE shows a small vegetation. The isolate is susceptible to ampicillin and gentamicin but has high-level gentamicin resistance (HLGR). What is the recommended treatment?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: B — Ampicillin plus gentamicin

For enterococcal endocarditis with high-level gentamicin resistance (HLGR), synergistic bactericidal activity with ampicillin + gentamicin is lost. The recommended alternative is ampicillin (2 g IV 4-hourly) PLUS ceftriaxone (2 g IV 12-hourly) for 6 weeks. This double beta-lactam regimen (first demonstrated in the Spanish endocarditis studies) achieves synergistic killing of enterococci through complementary PBP binding. It avoids the nephrotoxicity and ototoxicity of prolonged gentamicin. Treatment duration for prosthetic valve IE is 6 weeks minimum.

Reference: eTG – 2025 – Antibiotic Guidelines; ESC – 2023 – IE Guidelines