title: Resistance of canine methicillin-resistant Staphylococcus pseudintermedius strains to pradofloxacin.
abstract: We investigated in vitro activity of a novel veterinary fluoroquinolone, pradofloxacin, against methicillin-resistant Staphylococcus pseudintermedius (MRSP) isolates and compared with other fluoroquinolones. A total of 38 MRSP isolates were subjected to agar disk diffusion tests for sensitivity to pradofloxacin, orbifloxacin, marbofloxacin, enrofloxacin, and ciprofloxacin. The minimal inhibitory concentration (MIC) values of pradofloxacin, ciprofloxacin, and enrofloxacin were determined. Mutations in the genes encoding DNA gyrase subunit A (GyrA) and topoisomerase IV (GrlA) proteins associated with fluoroquinolone resistance were studied by an analysis of partial sequences of the genes encoding these proteins. Two MRSP isolates were susceptible in disk diffusion and microdilution test to all fluoroquinolones tested, including pradofloxacin. Based on the results of the disk diffusion testing, 33 of 38 isolates showed resistance to pradofloxacin and 3 were intermediate, whereas, by pradofloxacin MIC testing, 35 isolates were classified as resistant and 1 as intermediate. Single alterations in GyrA and GrlA proteins were observed in the 35 resistant isolates and the 1 intermediate isolate (MIC results). These same 36 isolates were also resistant to the other tested fluoroquinolones. The results of the current study showed that MRSP isolates are usually resistant to all fluoroquinolones, including pradofloxacin. Therefore, in routine susceptibility testing to pradofloxacin by disk diffusion, the results should be carefully interpreted for MRSP isolates, especially those resistant to other fluoroquinolones and, in questionable cases, the pradofloxacin MIC should be determined to confirm the susceptibility testing results.
authors.affiliation: Department of Preclinical Sciences, Faculty of Veterinary Medicine, Warsaw University of Life Sciences, Warsaw, Poland magdalena_kizerwetter_swida@sggw.pl.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Kizerwetter-Świda
authors.affiliation: Department of Preclinical Sciences, Faculty of Veterinary Medicine, Warsaw University of Life Sciences, Warsaw, Poland.
authors.forename: Dorota
authors.initials: D
authors.lastname: Chrobak-Chmiel
authors.affiliation: Department of Preclinical Sciences, Faculty of Veterinary Medicine, Warsaw University of Life Sciences, Warsaw, Poland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Rzewuska
authors.affiliation: Department of Preclinical Sciences, Faculty of Veterinary Medicine, Warsaw University of Life Sciences, Warsaw, Poland.
authors.forename: Marian
authors.initials: M
authors.lastname: Binek
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D004283:Dog Diseases / Q000188:drug therapy / Q000382:microbiology*; D004285:Dogs; D024841:Fluoroquinolones / Q000494:pharmacology* / Q000627:therapeutic use; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects*; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D013203:Staphylococcal Infections / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; C507250:pradofloxacin
keywords: Fluoroquinolone; methicillin-resistant Staphylococcus pseudintermedius; pradofloxacin resistance