title: Comparison of in vitro activities and pharmacokinetics/pharmacodynamics estimations of veterinary fluoroquinolones against avian pathogenic Escherichia coli isolates.
abstract: We analyzed in vitro activities and pharmacokinetics/pharmacodynamics (PK/PD) parameters of veterinary fluoroquinolones against avian pathogenic Escherichia coli (APEC) strains from cases of avian colibacillosis. The median of minimum inhibitory concentration (MIC(50)) values against APEC strains for enrofloxacin (ERFX) and danofloxacin (DNFX) were 0.25 μg/ml and for norfloxacin (NFLX) and ofloxacin (OFLX) were 0.5 μg/ml. The percentage of resistant strains for ERFX, DNFX, NFLX, and OFLX were 24.4%, 23.6%, 22.8%, and 23.6%, respectively. Scattergrams of the MICs of ERFX compared to DNFX, NFLX, and OFLX for 127 strains demonstrate a clear correlation between the MIC of ERFX and that of other fluoroquinolones. The differences in amino acid substitution in GyrA may play a role in the variation of MIC values for fluoroquinolones. The ratios of peak serum concentration to MIC (C(max):MIC) and ratios of area under the curve to MIC (AUC:MIC) were relatively high in ERFX and OFLX compared to other fluoroquinolones. These results indicate that although the in vitro activities of these fluoroquinolones against APEC isolates are slightly different, the PK/PD values vary with PK parameters. Therefore, we need to consider the PK/PD parameters in the choice of fluoroquinolones during treatment of avian colibacillosis.
authors.affiliation: National Veterinary Assay Laboratory, Ministry of Agriculture, Forestry, and Fisheries, Kokubunji, Tokyo, Japan. ozawa@nval.maff.go.jp
authors.forename: Manao
authors.initials: M
authors.lastname: Ozawa
authors.forename: Kotaro
authors.initials: K
authors.lastname: Baba
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Shimizu
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Asai
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D000900:Anti-Bacterial Agents / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D002645:Chickens / Q000382:microbiology*; D027081:DNA Gyrase / Q000235:genetics; D027101:DNA Topoisomerase IV / Q000235:genetics; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary*; D024841:Fluoroquinolones / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D008826:Microbial Sensitivity Tests; D011201:Poultry Diseases / Q000188:drug therapy* / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase