Modified time-kill assay against multidrug-resistant Enterococcus faecium with novel antimicrobial combinations.
This study used a modified time-kill assay to compare the in-vitro activity of chloramphenicol and quinopristin/dalfopristin combined with vancomycin, ampicillin or gentamicin against multidrug-resistant Enterococcus faecium. The assay uses standardized time-kill methods with the following modifications: centrifugation of the test tubes at 1-2 h intervals, removal of supernatant and resuspension of bacteria in media containing antibiotic concentrations corresponding to simulated steady-state serum concentrations. None of the agents, alone or in combination, produced bactericidal or synergic activity. The modified time-kill assay more closely simulates in-vivo conditions and may provide a better qualitative assay to determine the interaction between antimicrobial agents and bacteria.
Messick
C R
CR
Department of Veterans Affairs, Cooperative Studies Program, Clinical Research Pharmacy Coordinating Center, 2401 Center Avenue SE, Albuquerque, NM 87106-4180, USA.
Rodvold
K A
KA
Pendland
S L
SL
D000667:Ampicillin / Q000494:pharmacology; D002701:Chloramphenicol / Q000494:pharmacology; D015169:Colony Count, Microbial; D004352:Drug Resistance, Microbial; D018432:Drug Resistance, Multiple; D004359:Drug Therapy, Combination / Q000494:pharmacology*; D016984:Enterococcus faecium / Q000187:drug effects* / Q000254:growth & development; D005839:Gentamicins / Q000494:pharmacology; D007700:Kinetics; D008826:Microbial Sensitivity Tests / Q000379:methods*; D013997:Time Factors; D014640:Vancomycin / Q000494:pharmacology; D014769:Virginiamycin / Q000031:analogs & derivatives / Q000494:pharmacology
D005839:Gentamicins; D014769:Virginiamycin; D002701:Chloramphenicol; D014640:Vancomycin; D000667:Ampicillin; C113826:dalfopristin