title: In vitro activity of RPR 106972 alone and in combination with vancomycin, ampicillin, and gentamicin against multidrug-resistant enterococci.
abstract: This investigation used checkerboard and time-kill assays to evaluate the in vitro activity of RPR 106972 (45% pristinamycin IB and 55% pristinamycin IIB) alone and in combination with vancomycin or ampicillin +/- gentamicin against multidrug-resistant enterococci. The checkerboard procedure resulted in synergistic or additive effects in 91% of the isolates with the combination of RPR 106972 plus vancomycin versus 68% with RPR 106972 plus ampicillin. The addition of gentamicin to either combination resulted in synergistic or additive results in 100% of the isolates. Inhibitory activity was observed with the time-kill assay with mean change in log10 CFU/mL at 24 h of -0.31 for RPR 106972, 3.3 for vancomycin, -0.46 for RPR 106972 plus vancomycin, and -0.35 for RPR 106972 plus vancomycin and gentamicin. No antagonism was noted with any of the combinations. RPR 106972 demonstrates good inhibitory activity against Enterococcus faecium and may prove useful in the treatment of enterococcal infections.
authors.affiliation: Veterans Affairs Cooperative Studies Program, Clinical Research Pharmacy Coordinating Center, Albuquerque, New Mexico, USA.
authors.forename: C R
authors.initials: CR
authors.lastname: Messick
authors.forename: J
authors.initials: J
authors.lastname: Woodward
authors.forename: S L
authors.initials: SL
authors.lastname: Pendland
mesh_terms: D000667:Ampicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D018432:Drug Resistance, Multiple; D004357:Drug Synergism; D004359:Drug Therapy, Combination / Q000494:pharmacology*; D016983:Enterococcus / Q000187:drug effects* / Q000302:isolation & purification; D013293:Enterococcus faecalis / Q000187:drug effects / Q000302:isolation & purification; D016984:Enterococcus faecium / Q000187:drug effects / Q000302:isolation & purification; D005839:Gentamicins / Q000494:pharmacology; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology; D006801:Humans; D008826:Microbial Sensitivity Tests; D014640:Vancomycin / Q000494:pharmacology; D014769:Virginiamycin / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D005839:Gentamicins; C099364:RPR 106972; D014769:Virginiamycin; D014640:Vancomycin; D000667:Ampicillin