title: Ciprofloxacin as a representative of disk diffusion in vitro susceptibility of enrofloxacin for bacterial organisms from the middle-ear tissue of dogs with end-stage otitis externa.
abstract: The purposes of this study were to determine whether ciprofloxacin disk diffusion susceptibility test (DDT) results could be used to assess the in vitro susceptibility of otic bacterial organisms to enrofloxacin and to determine the effect of concurrent enrofloxacin administration on the DDT results for enrofloxacin and ciprofloxacin. Thirty dogs with end-stage otitis externa undergoing unilateral total ear canal ablation were enrolled. The dogs were randomized to one of four enrofloxacin-treatment groups or to the control group. Each dog in the treatment groups received two intravenous doses of enrofloxacin prior to surgical removal of the middle-ear tissue while the control group did not receive any enrofloxacin. One dog was excluded from the study as no middle-ear tissue was removed during surgery. Twenty-four dogs were in the enrofloxacin-treatment groups and five dogs were in the control group. In 12 of 29 dogs (41.4%), 14 of 82 (17.1%) of bacteria had discrepancies in DDT results for enrofloxacin and ciprofloxacin. Discrepancies between the control group and treatment groups were not significantly different even though the percentage of discrepancies for the combined treatment group was 19.4% compared to 6.7% for the control group. In this study, ciprofloxacin DDT results were not an accurate indicator of the in vitro susceptibility of enrofloxacin for bacteria isolated from the middle-ear tissue of dogs with end-stage otitis.
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, USA. cole.143@osu.edu
authors.forename: Lynette K
authors.initials: LK
authors.lastname: Cole
authors.forename: Kenneth W
authors.initials: KW
authors.lastname: Kwochka
authors.forename: Andrew
authors.initials: A
authors.lastname: Hillier
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Kowalski
authors.forename: Daniel D
authors.initials: DD
authors.lastname: Smeak
authors.forename: Nicole T
authors.initials: NT
authors.lastname: Kelbick
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology / Q000627:therapeutic use*; D002939:Ciprofloxacin / Q000494:pharmacology / Q000627:therapeutic use*; D004283:Dog Diseases / Q000188:drug therapy* / Q000382:microbiology / Q000473:pathology; D004285:Dogs; D000077422:Enrofloxacin; D005260:Female; D024841:Fluoroquinolones / Q000494:pharmacology / Q000627:therapeutic use*; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D008297:Male; D008826:Microbial Sensitivity Tests; D010032:Otitis Externa / Q000188:drug therapy / Q000662:veterinary*; D011237:Predictive Value of Tests; D012720:Severity of Illness Index
chemical_list: D000890:Anti-Infective Agents; D024841:Fluoroquinolones; D000077422:Enrofloxacin; D002939:Ciprofloxacin