Determination of the diversity and antibiotic resistance profiles of Staphylococcus species from dogs with otitis externa and examination of mecA gene occurrence

The aim of this study was to determine the distribution of Staphylococci from swab samples of dogs with otitis externa and to determine their antibiotic resistance profiles, particularly methicillin resistance. For this purpose 116 ear swab samples were collected from 100 dogs and examined for the presence of Staphylococcus species by conventional culture methods. Antibiotic susceptibility of the isolates was determined by the disk diffusion test and for methicillin resistance, by PCR. Forty Staphylococci were isolated from 37 (31.9%) of the 116 ear swabs. Among the 40 isolates, 30 of them were coagulase-positive Staphylococcus species (CPS), while 10 (25%) were coagulase-negative Staphylococcus spp. (CNS). S. pseudintermedius (n = 11), S. aureus (n = 8), other not determined Staphylococcus spp. (n = 7), S. chromogenes (n = 7), S. schleiferi coagulans (n = 3), S. hyicus (n = 1), S. hominis subsp. hominis (n = 1), S. simulans (n = 1), S. saprophyticus (n = 1) were isolated. Results of the antibiotic susceptibility tests have shown that 60% of the isolates were resistant to sulfamethoxazole/trimethoprim, 32.5% of them were resistant to erythromycin, 25% were resistant to clindamycin, and all isolates (100%) were sensitive to amoxicillin/clavulanic acid and cephazolin. The majority of isolates (97.5%) were sensitive to ciprofloxacin and gentamicin which are frequently used in otitis externa treatment. It was determined that only one (2.5%) (S. hominis subsp. hominis) of the 40 isolates was resistant to methicillin and carried the mecA gene. We found 77% of Staphylococcus spp. to be resistant to one or more antimicrobial drugs, and 25% of Staphylococcus species were found to be resistant to three or more antimicrobial classes. Thus, multidrug-resistance as detected in our study should always be taken into account and close attention should be given to the antimicrobial therapy protocols of pet animals.