title: Influence of high-level gentamicin resistance and beta-hemolysis on susceptibility of enterococci to the bactericidal activities of ampicillin and vancomycin.
abstract: The bactericidal activities of ampicillin and vancomycin against 40 recent isolates of Enterococcus faecalis were examined by kill-kinetic studies at concentrations of 4 x the MIC and 20 micrograms/ml. Greater killing was seen with ampicillin (3.57 +/- 0.87 and 2.50 +/- 1.09 log10 CFU/ml, respectively; mean +/- standard deviation) than with vancomycin (1.23 +/- 0.65 and 1.05 +/- 0.57 log10 CFU/ml, respectively). Highly gentamicin-resistant strains showed a tendency toward reduced susceptibility to killing; beta-hemolytic strains were more susceptible than nonhemolytic strains when exposed to ampicillin at 20 micrograms/ml. Within each group, individual isolates demonstrated great variability in susceptibility to killing by the drugs.
authors: Department of Medicine, New England Deaconess Hospital, Boston, Massachusetts 02115.
authors: E
authors: E
authors: Cercenado
authors: G M
authors: GM
authors: Eliopoulos
authors: C B
authors: CB
authors: Wennersten
authors: R C
authors: RC
authors: Moellering
mesh_terms: D000667:Ampicillin / Q000494:pharmacology*; D004352:Drug Resistance, Microbial / Q000502:physiology; D013293:Enterococcus faecalis / Q000187:drug effects*; D005839:Gentamicins / Q000494:pharmacology*; D006461:Hemolysis / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D015203:Reproducibility of Results; D014640:Vancomycin / Q000494:pharmacology*
chemical_list: D005839:Gentamicins; D014640:Vancomycin; D000667:Ampicillin