Gentamicin may have no effect on mortality of staphylococcal prosthetic valve endocarditis

To analyze the influence of adding gentamicin to a regimen consisting of β-lactam or vancomycin plus rifampicin on survival in patients suffering from Staphylococcal prosthetic valve endocarditis (SPVE). From January 2008 to September 2016, 334 patients with definite SPVE were attended in the participating hospitals. Ninety-four patients (28.1%) received treatment based on β-lactam or vancomycin plus rifampicin and were included in the study. Variables were analyzed which related to patient survival during admission, including having received treatment with gentamicin. Seventy-seven (81.9%) were treated with cloxacillin (or vancomycin) plus rifampicin plus gentamicin, and 17 patients (18.1%) received the same regimen without gentamicin. The causative microorganism was Staphylococcus aureus in 40 cases (42.6%) and coagulase-negative staphylococci in 54 cases (57.4%). Overall, 40 patients (42.6%) died during hospital admission, 33 patients (42.9%) in the group receiving gentamicin and 7 patients in the group that did not (41.2%, P = 0.899). Worsening renal function was observed in 42 patients (54.5%) who received gentamicin and in 9 patients (52.9%) who did not (p = 0.904). Heart failure as a complication of endocarditis (OR: 4.58; CI 95%: 1.84–11.42) and not performing surgery when indicated (OR: 2.68; CI 95%: 1.03–6.94) increased mortality. Gentamicin administration remained unrelated to mortality (OR: 1.001; CI 95%: 0.29–3.38) in the multivariable analysis. The addition of gentamicin to a regimen containing vancomycin or cloxacillin plus rifampicin in SPVE was not associated to better outcome.