Synergic activity of vancomycin-quinupristin/dalfopristin combination against Enterococcus faecium.
Clinical specimens were cultured, and the strains identified by the Vitek system as Enterococcus faecium were characterized by their DNA. The MIC vancomycin, quinupristin/dalfopristin and teicoplanin for each isolate was determined. Ten vancomycin-sensitive and ten vancomycin-resistant strains of E. faecium were tested. Quinupristin/dalfopristin at 0.25 x MIC and vancomycin at 0.5 x MIC separately as well as in combination were added to Trypticase Soy Broth tubes inoculated with a 24 h culture. The results obtained by determining cfu at 2, 4, 8, 12 and 24 h indicated that the combination of subinhibitory concentrations of quinupristin/dalfopristin plus vancomycin produced after 24 h, in vancomycin-resistant strains, a consistent degree of synergy. Synergy was observed up to only 12 h when similar combinations were employed for vancomycin-sensitive strains. Vancomycin-sensitive strains tended to be slightly less susceptible to quinupristin/dalfopristin than vancomycin-resistant strains.
Lorian
V
V
Bronx Lebanon Hospital Center, NY 10457, USA.
Fernandes
F
F
D015169:Colony Count, Microbial; D004357:Drug Synergism; D004359:Drug Therapy, Combination / Q000494:pharmacology*; D016984:Enterococcus faecium / Q000187:drug effects* / Q000254:growth & development; D006801:Humans; D008826:Microbial Sensitivity Tests; D014640:Vancomycin / Q000494:pharmacology*; D014769:Virginiamycin / Q000494:pharmacology*
D014769:Virginiamycin; C062940:quinupristin-dalfopristin; D014640:Vancomycin