Evaluation of penicillin-gentamicin and dual beta-lactam therapies in Enterococcus faecalis infective endocarditis

The American Heart Association endorses penicillin G or ampicillin with gentamicin (A+G) or dual beta-lactam therapy with ampicillin and ceftriaxone (A+C) as first-line regimens for Enterococcus faecalis infective endocarditis (EFIE) caused by penicillin-susceptible isolates.

To compare rates of treatment modifications and failures among individuals treated with A+C vs. A+G therapies for EFIE.

This study was a retrospective, single-centre cohort of adult patients with EFIE treated with A+G or A+C therapy between July 2009 and July 2019. The primary outcome was rate of adverse events requiring treatment modification. Secondary outcomes included rates of any event requiring treatment modification and treatment failure.

Fifty-nine individuals with EFIE who received A+G (17 patients) or A+C (42 patients) therapy were included. Community-acquired EFIE from an unknown source was the most common (67.8%). Rates of adverse events requiring treatment modifications were 52.9% in A+G and 16.7% in A+C group (P = 0.005). Treatment modification was most frequently due to nephrotoxicity in the A+G group (90.0%). Incidence of acute kidney injury was 41.2% in A+G vs. 11.9% in the A+C group (P = 0.011). Rates of any event requiring treatment modifications were 58.8% in the A+G and 23.8% in A+C groups (P = 0.010). Treatment failure was observed in 23.5% in the A+G and 28.6% in A+C groups (P = 0.759).

An A+C regimen may provide a tolerable and equally efficacious option for treatment of EFIE in adults and confirms the American Heart Association guideline recommendation.