High genetic diversity and multidrug resistance in methicillin-resistant Staphylococcus pseudintermedius from companion animals in South Korea between 2021 and 2023

OBJECTIVES: Methicillin-resistant Staphylococcus pseudintermedius (MRSP) is an emerging multidrug-resistant pathogen with zoonotic potential. This study investigated the antimicrobial resistance, genomic diversity, and virulence characteristics of MRSP isolates from companion animals in South Korea. METHODS: We analyzed 68 MRSP isolates collected from dogs and cats with skin or ear infections in Seoul between 2021 and 2023 using antimicrobial susceptibility testing and whole-genome sequencing. Antimicrobial resistance genes, staphylococcal cassette chromosome mec (SCCmec) types, multilocus sequence types (STs), virulence factors, and phylogenetic relationships were determined. RESULTS: All isolates were resistant to penicillin and oxacillin. High resistance rates were observed for cefovecin (98.5%) and tetracycline (89.7%). Sixty-seven isolates (98.5%) were resistant to at least three antimicrobial categories, with two resistant to ten classes. Multilocus sequence typing revealed 42 STs, including 11 novel STs; ST2842 (8.8%) and ST361 (7.4%) were most frequent. The mecA gene was universally present, and blaZ was detected in 97.1% of isolates. SCCmec typing identified type V (5C2&5) as predominant. Virulence profiling identified 60 of 67 investigated genes (89.6%) in at least one genome, with 39 genes (58.2%) conserved across all isolates. Phylogenomic analysis showed high genomic diversity but also close relatedness to human isolates. CONCLUSIONS: This study provides the first comprehensive genomic characterization of MRSP from companion animals in South Korea. The detection of strains closely related to human isolates underscores the likelihood of interspecies transmission. These findings highlight MRSP as a critical public health threat and the urgent need for surveillance and coordinated control strategies to limit its spread.

Authors: Y. R. Seo, S. Y. Choi, J. Y. Kim, S. Kim, K. S. Kang, C. S. Ro, S. Hwang and J. Y. Hyeon Title: High genetic diversity and multidrug resistance in methicillin-resistant Staphylococcus pseudintermedius from companion animals in South Korea between 2021 and 2023 Full source: J Glob Antimicrob Resist, 2026,Vol Document type: Journal Article
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OBJECTIVES: Methicillin-resistant Staphylococcus pseudintermedius (MRSP) is an emerging multidrug-resistant pathogen with zoonotic potential. This study investigated the antimicrobial resistance, genomic diversity, and virulence characteristics of MRSP isolates from companion animals in South Korea. METHODS: We analyzed 68 MRSP isolates collected from dogs and cats with skin or ear infections in Seoul between 2021 and 2023 using antimicrobial susceptibility testing and whole-genome sequencing. Antimicrobial resistance genes, staphylococcal cassette chromosome mec (SCCmec) types, multilocus sequence types (STs), virulence factors, and phylogenetic relationships were determined. RESULTS: All isolates were resistant to penicillin and oxacillin. High resistance rates were observed for cefovecin (98.5%) and tetracycline (89.7%). Sixty-seven isolates (98.5%) were resistant to at least three antimicrobial categories, with two resistant to ten classes. Multilocus sequence typing revealed 42 STs, including 11 novel STs; ST2842 (8.8%) and ST361 (7.4%) were most frequent. The mecA gene was universally present, and blaZ was detected in 97.1% of isolates. SCCmec typing identified type V (5C2&5) as predominant. Virulence profiling identified 60 of 67 investigated genes (89.6%) in at least one genome, with 39 genes (58.2%) conserved across all isolates. Phylogenomic analysis showed high genomic diversity but also close relatedness to human isolates. CONCLUSIONS: This study provides the first comprehensive genomic characterization of MRSP from companion animals in South Korea. The detection of strains closely related to human isolates underscores the likelihood of interspecies transmission. These findings highlight MRSP as a critical public health threat and the urgent need for surveillance and coordinated control strategies to limit its spread.