title: In vitro potency and efficacy favor later generation fluoroquinolones for treatment of canine and feline Escherichia coli uropathogens in the United States.
abstract: Information regarding in vitro activity of newer fluoroquinolones (FQs) is limited despite increasing resistance in canine or feline pathogenic Escherichia coli (E. coli). This study describes in vitro potency and efficacy toward E. coli of seven FQs grouped according to similarities in chemical structure: enrofloxacin, ciprofloxacin, orbifloxacin (first-group), levofloxacin, marbofloxacin (second-group) and pradofloxacin, moxifloxacin (third-group; latest S, S-pyrrolidino-piperidine at C-7). Potency measures included minimum inhibitory concentration (MIC) (geometric mean MIC, MIC(50), MIC(90)); and mutant prevention concentration (MPC) for FQ susceptible isolates only. In vitro efficacy measures included relative susceptibility (MIC(BP-S):MIC) or resistance (MIC:MIC(BP-R)) and mutant selection window (MSW) (MPC:MIC). For enrofloxacin susceptible isolates, mean MIC (μg/ml) was least for each third-group drug and ciprofloxacin and greatest for enrofloxacin and orbifloxacin (P = 0.006). For enrofloxacin susceptible isolates, MPC were below MIC:MIC(BP-R) and least for pradofloxacin (0.29 ± 0.16 μg/ml) and greatest for enrofloxacin (1.55 ± 0.55 μg/ml) (P = 0.006). MSW was least for pradofloxacin (55 ± 30) and greatest for ciprofloxacin (152 ± 76) (P = 0.0024). MIC(BP-S):MIC was greatest (P = 0.025) for pradofloxacin (190.1 ± 0.61) and least for enrofloxacin (23.53 ± 0.83). For FQ susceptible isolates, FQs MIC:MIC(BP-R) may serve as a surrogate for MPC. Because in vitro efficacy was greatest for pradofloxacin; it might be preferred for treatment of urinary tract infections (UTIs) associated with FQ susceptible E. coli uropathogens.
authors.affiliation: College of Veterinary Medicine, Northwest A&F University, Yangling 712100, Shaanxi, People's Republic of China.
authors.forename: Xiaoqiang
authors.initials: X
authors.lastname: Liu
authors.forename: Dawn M
authors.initials: DM
authors.lastname: Boothe
authors.forename: Yaping
authors.initials: Y
authors.lastname: Jin
authors.forename: Kamoltip
authors.initials: K
authors.lastname: Thungrat
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D002371:Cat Diseases / Q000188:drug therapy / Q000382:microbiology*; D002415:Cats; D004283:Dog Diseases / Q000188:drug therapy / Q000382:microbiology*; D004285:Dogs; D024881:Drug Resistance, Bacterial; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000382:microbiology / Q000662:veterinary*; D024841:Fluoroquinolones / Q000737:chemistry / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D015394:Molecular Structure; D014481:United States; D056689:Uropathogenic Escherichia coli / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones