Enterococcus faecalis Infective Endocarditis: A Pilot Study of the Relationship Between Duration of Gentamicin Treatment and Outcome

Study Questions:

What are the outcomes in patients with Enterococcus faecalis infective endocarditis treated with adjunctive gentamicin for 4-6 weeks versus only 2 weeks?


A total of 84 consecutive patients admitted with definite left-sided E faecalis endocarditis, from 2002 to 2011, were enrolled. Forty-one patients were treated before and 43 patients were treated after January 1, 2007. One-year overall survival was compared between groups through the use of Kaplan-Meier survival curves and the log-rank test to estimate differences in survival.


There were no significant differences in baseline characteristics. At hospitalization, the two groups had similar estimated glomerular filtration rates of 66 and 75 ml/min (p = 0.22). Patients treated before January 2007, received gentamicin for a significantly longer period (28 vs. 14 days; p < 0.001). The primary outcome, 1-year event-free survival, did not differ (66% vs. 69%, respectively; p = 0.75). At discharge, the patients treated before 2007 had a lower estimated glomerular filtration rate (45 vs. 66 ml/min; p = 0.008) and a significantly greater decrease in estimated glomerular filtration rate (median, 11 vs. 1 ml/min; p = 0.009) compared with those treated after 2007.


The authors concluded that the recommended 2-week treatment with gentamicin seems adequate and preferable in treating non–high-level aminoglycoside-resistant E faecalis infective endocarditis.


The principal finding of this pilot study is that antibiotic treatment of non–high-level aminoglycoside-resistant E faecalis infective endocarditis starting out with a β-lactam combined with 2 weeks of gentamicin appears to provide event-free survival similar to a combination with 4-6 weeks of gentamicin treatment. Furthermore, the deleterious effect on renal function induced by prolonged gentamicin administration is avoided. Given the small sample size, larger randomized, controlled studies are warranted to substantiate these results, but for now, a 2-week course of adjunctive aminoglycoside therapy appears adequate.

Keywords: Kaplan-Meier Estimate, Endocarditis, Gentamicins, Glomerular Filtration Rate, Enterococcus faecalis

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