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The following is a summary of “Combination therapy versus monotherapy: retrospective analysis of antibiotic treatment of enterococcal endocarditis,” published in the January 2025 issue of Infectious Disease by Saman et al. 

Current guidelines recommend combination therapy with amoxicillin and either gentamicin or ceftriaxone for treating fully penicillin-susceptible Enterococcus faecalis infective endocarditis despite limited clinical evidence and the exclusion of monotherapy cohorts in existing studies.  

Researchers conducted a retrospective study to compare antibiotic monotherapy vs combination therapy in patients with Enterococcus faecalis infective endocarditis, focusing on treatment, complications, and outcomes.  

They analyzed individuals with definite or possible infective endocarditis from 2 English centers between 2006 and 2021. The primary outcome was 30-day mortality, while the secondary outcomes included acute kidney injury, relapse, and clinical cure.  

The results showed 178 individuals with a median age of 72 years (interquartile range 60–79), predominantly male (138, 78%), and mostly with native valve endocarditis (108, 61%), 39 individuals (22%) received monotherapy (penicillin/glycopeptide/linezolid/daptomycin), 128 (72%) received combination therapy with gentamicin, and 11 (6%) received combination therapy with ceftriaxone. Combination therapy with gentamicin was associated with lower 30-day mortality (21 (16.4%) vs 15 (38.5%), P = 0.035) and higher clinical cure rates (101 (78.9%) vs 23 (59.0%), P = 0.018) compared to monotherapy. Patients receiving gentamicin were more likely to experience acute kidney injury (64 (50%) vs 11 (28.2%), P = 0.057). Ceftriaxone combination therapy was linked to poorer outcomes, though the sample size was small.  

Investigators concluded the individuals treated with combination gentamicin therapy had better clinical outcomes than those treated with monotherapy, although low-dose gentamicin regimens were linked to acute kidney injury, and confounding factors remained a concern in observational analyses, highlighting the need for an adequately powered clinical trial to determine the optimal treatment for enterococcal endocarditis. 

Source: bmcinfectdis.biomedcentral.com/articles/10.1186/s12879-025-10451-2