Antimicrobial resistance of methicillin-resistant staphylococci isolates from dog ears in Korea

Methicillin-resistant staphylococci (MRS), which are often multi-drug resistant (MDR), are important pathogens in both human and veterinary healthcare. The purpose of this study was to characterize the antimicrobial resistance of MRS isolated from dog ears in Korea. From 827 dog ears, staphylococci were cultured from both ears with otitis externa (n = 161, 41.0%) and healthy ears (n = 135, 31.1%). The prevalence of coagulase-positive staphylococci (CoPS) in ears with otitis externa (58.4%) was significantly higher (p < 0.05) than in healthy ears (28.2%), while the prevalence of coagulase-negative staphylococci (CoNS) in healthy ears (74.8%) was higher (P < 0.05) than in ears with otitis externa (41.6%). Forty-six (35.1%) and 74 (44.8%) CoPS and CoNS isolates, respectively, were determined to be MRS. Antimicrobial resistance in MRS was most frequently observed for penicillin (76.7%), ampicillin (61.7%), kanamycin (61.7%), erythromycin (47.5%), tetracycline (47.5%), and trimethoprim/sulfamethoxazole (46.7%). Overall, the MDR isolates were resistant to significantly more (P < 0.05) antimicrobial agents tested than methicillin-sensitive staphylococci in this study. These results provide therapeutic guidelines for the treatment of otitis externa in dogs from Korean veterinary hospitals, and the significant associated health concern to companion animals and their human contacts.