title: In vitro bactericidal activity of daptomycin against staphylococci.
abstract: MICs and minimum bactericidal concentrations (MBCs) of daptomycin, vancomycin, linezolid and quinupristin-dalfopristin (Q-D) were determined for 108 staphylococcal isolates. All strains were susceptible (MICs) to daptomycin (< or =2.0 mg/L) and Q-D (< or =1.0 mg/L). All but three isolates were susceptible to vancomycin (< or =4.0 mg/L) and all but one methicillin-resistant Staphylococcus aureus strain were susceptible to linezolid (< or =4.0 mg/L). Q-D had the lowest geometric mean MIC (0.29 mg/L) and daptomycin had the lowest geometric mean MBC (0.57 mg/L). Time-kill tests were performed on 25 isolates. Bactericidal activity (>99.9% kill) was observed with daptomycin at 2 mg/L and at 2 x MBC for 92% of strains tested. In comparison, the bactericidal rates for the other drugs at breakpoint concentrations and at 2 x MBC were 72% and 70% for vancomycin, 46% and 60% for Q-D, and 7% and 14% for linezolid. Of the four drugs tested, daptomycin was bactericidal against the most strains and had the most rapid cidal activity.
authors.affiliation: The Clinical Microbiology Institute, 9725 SW Commerce Circle, Wilsonville, OR 97070, USA. cmi@hevanet.com
authors.forename: Peter C
authors.initials: PC
authors.lastname: Fuchs
authors.forename: Arthur L
authors.initials: AL
authors.lastname: Barry
authors.forename: Steven D
authors.initials: SD
authors.lastname: Brown
mesh_terms: D000081:Acetamides / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D017576:Daptomycin / Q000494:pharmacology*; D004359:Drug Therapy, Combination / Q000494:pharmacology; D000069349:Linezolid; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests; D023303:Oxazolidinones / Q000494:pharmacology; D013203:Staphylococcal Infections / Q000382:microbiology; D013210:Staphylococcus / Q000187:drug effects* / Q000302:isolation & purification; D014640:Vancomycin / Q000494:pharmacology; D014769:Virginiamycin / Q000494:pharmacology
chemical_list: D000081:Acetamides; D000900:Anti-Bacterial Agents; D023303:Oxazolidinones; D014769:Virginiamycin; C062940:quinupristin-dalfopristin; D014640:Vancomycin; D000069349:Linezolid; D017576:Daptomycin