Characterization of Methicillin-Resistant Staphylococcus pseudintermedius Isolated from Dogs in Veterinary Hospitals in Korea

Methicillin-resistant Staphylococcus pseudintermedius (MRSP) has emerged as an important health threat in companion animals, with potential for transmission to humans. However, little is known about MRSP circulating in Korea. Accordingly, in this study, we determined the prevalence, antimicrobial resistance profile' and clonal distribution of MRSP in Korea. Forty of 57 (70.17%) swab samples collected from dogs at five veterinary hospitals were positive for S. pseudintermedius (SP), and 21 dogs (36.84%) were carrying MRSP strains. Overall, 26 of 50 isolates (52.0%) were MRSP. Antimicrobial susceptibility tests against 18 antimicrobial agents (13 classes) revealed that all MRSP were multi-drug resistant isolates showing resistance to a wide range of antimicrobial classes. Compared to susceptible isolates, MRSP isolates showed higher resistance rates to most antimicrobials, including oxacillin (100%), cefazolin (96.2%), cefoxitin (96.2%), cefotaxime (100%), and trimethoprim-sulfamethoxazole (100%). Multilocus sequence typing revealed 27 distinct sequence types without a predominant type, including 22 novel types and 3 novel clonal complexes, indicating independently evolving lineages in Korea. Future studies on clones that will evolve to be a major clonal lineage in Korea could give us an important insight regarding the key factors related to the widespread of selected clones in the world.