Efficacy of ampicillin plus arbekacin in experimental rabbit endocarditis caused by an Enterococcus faecalis strain with high-level gentamicin resistance.

Enterococcus faecalis LC40 is an ampicillin-susceptible clinical isolate with high-level gentamicin resistance due to the aac(6')-Ie-aph(2 ")-Ia aminoglycoside resistance gene. The combination of ampicillin plus arbekacin reduced mean bacterial vegetation counts significantly more than ampicillin alone or ampicillin pins gentamicin in a rabbit model of aortic-valve endocarditis caused by E. faecalis LC40.