Gentamicin once-daily in enterococcal endocarditis

Enterococcal endocarditis represents the third cause of infectious endocarditis (IE) following staphylococcal and streptococcal species and reaching up to 20% of all cases. Recently revised guidelines recommend the use of beta-lactams in association with gentamicin administered twice or three times daily for IE due to enterococcal strains that are documented to be susceptible to these compounds [2] and [3]. Enterococci are relatively impermeable to aminoglycosides. Cell wall-active agents (i.e., beta-lactams or glycopeptides) increase the permeability of the enterococcal membrane, and hence a bactericidal effect can be achieved by diffusion of the aminoglycoside at adequate concentrations without excessive toxicity. Thus, high concentration of aminoglycosides in the extracellular milieu during co-treatment with cell wall-active agents might allow increased drug level at the site of the ribosomal target within the bacterial cell for bactericidal activity. Accordingly, gentamicin once-daily administration should optimize Cmax/MIC ratio maximizing the efficacy and reducing the toxicity. Interestingly, favorable clinical outcome in the treatment of Enterococcus faecalis endocarditis using once-daily (OD) aminoglycoside regimen was previously and recently reported [4] and [5]. Our aim was therefore to report clinical and pharmacological data of patients with documented enterococcal IE treated with a single daily dose of gentamicin