title: Mutant prevention concentration of garenoxacin (BMS-284756) for ciprofloxacin-susceptible or -resistant Staphylococcus aureus.
abstract: The new quinolone garenoxacin (BMS-284756), which lacks a C-6 fluorine, was examined for its ability to block the growth of Staphylococcus aureus. Measurement of the MIC and the mutant prevention concentration (MPC) revealed that garenoxacin was 20-fold more potent than ciprofloxacin for a variety of ciprofloxacin-susceptible isolates, some of which were resistant to methicillin. The MPC for 90% of the isolates (MPC(90)) was below published serum drug concentrations achieved with recommended doses of garenoxacin. These in vitro observations suggest that garenoxacin has a low propensity for selective enrichment of fluoroquinolone-resistant mutants among ciprofloxacin-susceptible isolates of S. aureus. For ciprofloxacin-resistant isolates, the MIC at which 90% of the isolates tested were inhibited was below serum drug concentrations while the MPC(90) was not. Thus, for these strains, garenoxacin concentrations are expected to fall inside the mutant selection window (between the MIC and the MPC) for much of the treatment time. As a result, garenoxacin is expected to selectively enrich mutants with even lower susceptibility.
authors.affiliation: Public Health Research Institute, Newark, New Jersey 07103, USA.
authors.forename: Xilin
authors.initials: X
authors.lastname: Zhao
authors.forename: William
authors.initials: W
authors.lastname: Eisner
authors.forename: Nathan
authors.initials: N
authors.lastname: Perl-Rosenthal
authors.forename: Barry
authors.initials: B
authors.lastname: Kreiswirth
authors.forename: Karl
authors.initials: K
authors.lastname: Drlica
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology*; D002939:Ciprofloxacin / Q000494:pharmacology*; D004269:DNA, Bacterial / Q000737:chemistry; D024881:Drug Resistance, Bacterial; D024841:Fluoroquinolones; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D009154:Mutation / Q000235:genetics; D015363:Quinolones / Q000494:pharmacology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013203:Staphylococcal Infections / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics*
chemical_list: D000890:Anti-Infective Agents; D004269:DNA, Bacterial; D024841:Fluoroquinolones; D007211:Indoles; D015363:Quinolones; D002939:Ciprofloxacin; C419689:garenoxacin