Impact of inoculum size and heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) on vancomycin activity and emergence of VISA in an in vitro pharmacodynamic model.
The activity of vancomycin against heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) and non-hVISA isolates, using an in vitro pharmacodynamic model, was reduced in the presence of a high inoculum amount (10(8) CFU/ml). A high bacterial load of >10(5) CFU/ml persisted for all strains with doses up to 5 g every 12 h against high inoculum amounts. No change in the vancomycin MIC was detected in any isolate at a moderate inoculum amount (10(6) CFU/ml), and bactericidal activity occurred only against the non-hVISA isolate (time to 99% kill, 7.5 h; P = 0.001).
Rose
Warren E
WE
Department of Pharmacy Practice, Eugene Applebaum College of Pharmacy and Health Sciences, Detroit, Michigan 48201, USA.
Leonard
Steven N
SN
Rossi
Kerri L
KL
Kaatz
Glenn W
GW
Rybak
Michael J
MJ
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015169:Colony Count, Microbial; D003198:Computer Simulation; D006801:Humans; D008826:Microbial Sensitivity Tests; D013203:Staphylococcal Infections / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects*; D014640:Vancomycin / Q000494:pharmacology*; D020713:Vancomycin Resistance / Q000187:drug effects*
D000900:Anti-Bacterial Agents; D014640:Vancomycin