title: Activity of new quinolones against ciprofloxacin-resistant staphylococci.
abstract: Because of the development of newer fluoroquinolones with improved activity against gram-positive organisms, we elected to compare the inhibitory properties of ofloxacin, temafloxacin, sparfloxacin, PD131628, PD127391, and WIN57273 against 105 ciprofloxacin-resistant staphylococci. Based on comparison of MICs for 90% of the organisms (MIC90s), WIN57273 was the most active agent against oxacillin-resistant Staphylococcus aureus; the MIC90 was 0.5 microgram/ml. Against oxacillin-resistant, coagulase-negative staphylococci, PD127391 and WIN57273 were the most active agents; the MIC90 was 0.5 microgram/ml. Against isolates of staphylococci for which ciprofloxacin MICs were greater than or equal to 32 micrograms/ml, WIN57273 and PD127391 still exhibited high activity, inhibiting 100 and 95% of the isolates, respectively, at 2 micrograms/ml. The spontaneous mutation rates for ciprofloxacin-susceptible staphylococci were lowest for ofloxacin. The frequency of spontaneous mutations of ciprofloxacin-resistant staphylococci was low; however, the MICs of PD127391 and WIN57273 for these mutant isolates were greater than 2 micrograms/ml. WIN57273 and PD127391 are two potent new quinolones with high levels of activity against highly ciprofloxacin-resistant staphylococci. There is, however, a major concern of selection of spontaneous mutants resistant to these newer agents.
authors.affiliation: Cleveland Clinic Foundation, Ohio 44195.
authors.forename: G J
authors.initials: GJ
authors.lastname: Forstall
authors.forename: C C
authors.initials: CC
authors.lastname: Knapp
authors.forename: J A
authors.initials: JA
authors.lastname: Washington
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology; D002939:Ciprofloxacin / Q000494:pharmacology; D004352:Drug Resistance, Microbial; D024841:Fluoroquinolones; D008826:Microbial Sensitivity Tests; D009287:Naphthyridines; D015242:Ofloxacin / Q000494:pharmacology; D015363:Quinolones / Q000494:pharmacology*; D013210:Staphylococcus / Q000187:drug effects*
chemical_list: D000890:Anti-Infective Agents; D024841:Fluoroquinolones; D009287:Naphthyridines; D015363:Quinolones; C062556:Win 57273; C068217:PD 131628; C054745:temafloxacin; D002939:Ciprofloxacin; C057477:clinafloxacin; D015242:Ofloxacin; C061363:sparfloxacin