Influence of gentamicin dosing interval on the efficacy of penicillin-containing regimens in experimental Enterococcus faecalis endocarditis

Abstract

The influence of the gentamicin dosing regimen was studied in experimental Enterococcus faecalis endocarditis. After inoculation, animals received penicillin, or penicillin plus once-daily gentamicin, or penicillin plus thrice-daily gentamicin, or no treatment. After the treatment period, bacterial densities within the vegetations (mean ± SEM) were 6.06 ± 0.30, 5.42 ± 0.29, 4.98 ± 0.10 and 9.97 ± 0.16 log cfu/g for the four groups. All regimens produced significant reductions in bacterial density when compared with controls; penicillin plus thrice-daily gentamicin resulted in a significant difference from penicillin alone. Although once-daily regimens have proved effective in trials involving other organisms, such regimens do not appear to be so optimal for the treatment of enterococcal endocarditis.