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 plus gentamicin in a rabbit model of aortic-valve endocarditis caused by E. faecalis LC40.