Characterization and in vitro susceptibility profile of bacterial samples harvest from canine chronic otitis

This study aimed to identify which are the most frequent bacteria evolved in cases of chronic otitis in dogs in the metropolitan region of Curitiba, as well to determine their in vitro antimicrobial susceptibility. Data of positive bacterial culture from dogs affected by chronic or recurrent otitis were compiled from the records of the veterinary hospital of Pontifícia Universidade Católica do Paraná, Curitiba, southern Brazil. In a period of 16 months, a total of 83 bacterial cultures were performed, resulting in 192 isolates. All isolates were submitted to antimicrobial susceptibility tests, based on the Kirby-Bauer technique using 17 drugs from 8 antibiotic classes (?-lactams, aminoglycosides, lincosamides, macrolides, polypeptides, quinolones, tetracyclines, and amphenicols). The five most frequent bacterial isolates were Staphylococcus spp. (58.32%), Proteus spp. (14.58%), Escherichia coli (9.90%) and Pseudomonas spp. (8.33%). The four most effective antibiotics were amikacin (13.29%), neomycin (24.47%), gentamicin (25.52%) and tobramycin (26.70%); however, these aminoglycosides may cause ototoxicity, and their use should be restricted when the tympanic membrane is intact. Quinolones also showed antimicrobial effectiveness, with 29.17% of the isolates showing resistance to ciprofloxacin and 29.69% to enrofloxacin. According to the results, it can be concluded that aminoglycosides and quinolones were effective against microorganisms of canine chronic otitis.