Phenotypic and Molecular Characterization of Antimicrobial Resistance in Canine Staphylococci from North Macedonia

Abstract Antimicrobial resistance (AMR) in Staphylococcus spp. is a growing problem in small animal practice, driven by the emergence of methicillin-resistant (MR) and multidrug-resistant (MDR) strains. This study analyzed 170 clinical Staphylococcus isolates from dogs in North Macedonia, using MALDI-TOF MS identification, disc diffusion susceptibility testing, and molecular detection of resistance genes ( mec A, mec C, and bla Z). Staphylococcus pseudintermedius was identified as the most prevalent species (90%), followed by S. aureus (7.6%), S. hemolyticus (1.2%), S. schleiferi (0.6%), and S. intermedius (0.6%). Methicillin resistance was detected in 28.8% of the isolates by detecting mec A. Importantly, there was a significant discrepancy between phenotypic oxacillin resistance and mec A-positive isolates in S. pseudintermedius . Among the 49 mec A-negative but oxacillin-resistant isolates tested for bla Z, 65.3% were bla Z-positive, underscoring the critical role of beta-lactamase-mediated resistance. Overall, MDR was detected in 70.5% of isolates. High resistance was observed to multiple antibiotics, including penicillin G (73%) and clindamycin (61.8%), as well as critically important antibiotics (CIAs), such as fluoroquinolones, with resistance rates of 32.3% for enrofloxacin and 31.2% for marbofloxacin. Pradofloxacin showed the lowest resistance rate (22.3%). This study highlights the high prevalence of antimicrobial resistance in Staphylococcus spp. in dogs. Implementation of antimicrobial stewardship programs is critical to maintain the efficacy of key antimicrobials and ensure optimal treatment outcomes for companion animals in North Macedonia.