What question did this study set out to answer?

The study aims to reconstruct the evolutionary history and population structure of MRSA in Korea.

February 26, 2026Open Access

Comparative Genomic and Epidemiologic Analysis of Methicillin-Resistant Staphylococcus aureus Isolates in Republic of Korea

Key Points

The study aims to reconstruct the evolutionary history and population structure of MRSA in Korea.
Analyzed 191 MRSA clinical isolates from four biobanks in Korea collected between 1999 and 2025.
Conducted whole-genome sequencing and used international MRSA genomes as controls.
Performed phylogenomic analysis using SNPs, PCA, and ADMIXTURE for distribution assessment.
Executed a time-scale epidemiological analysis based on SNP phylogenetics.
Annotated antimicrobial resistance and virulence factor genes via ResFinder and VirulenceFinder.
Identified five major MRSA clades with distinct characteristics and evolutionary timelines.
Concluded that major clades diverged in the early 20th century, with clade 1 splitting around 1918.
Korean ST5 isolates showed significant divergence from North American strains starting in the 1960s.
ST72 formed an independent clade closer to clade 4 rather than the canonical CC8 group.
ST1 isolates demonstrated a temporal division into older and more recent lineages with expanded resistance profiles.

Abstract

Background/Objectives: Methicillin-resistant Staphylococcus aureus (MRSA) is a major causative pathogen in Republic of Korea. While numerous variants exist, the long-term evolutionary history of indigenous lineages remains unclear. Therefore, this study aimed to reconstruct the high-resolution population structure of Korean MRSA. Methods: A total of 191 MRSA clinical isolates collected between 1999 and 2025 were obtained from four Korean biobanks. Whole-genome sequencing was conducted and international MRSA genomes from the National Center for Bioinformatics were used as a control group. A genome-wide association study, including single-nucleotide polymorphism (SNP)-based phylogenomic analysis, principal component analysis (PCA), and ADMIXTURE, was performed for distribution analysis. A time-scale epidemiological analysis was conducted using SNP-based phylogenetic data. Additional profiling was performed via core genome multilocus sequence typing (cgMLST) for comparison with the SNP-based phylogenomic results. Finally, antimicrobial resistance and virulence factor genes were annotated using the ResFinder and VirulenceFinder databases. Results: Phylogenetic analysis identified five major clades: 1 (ST5), 2 (ST6), 3 (ST72), 4 (ST1/ST188), and 5 (ST8/ST239/ST254). Time-scaled analysis estimated that these major clades began to diverge in the early 20th century (e.g., Clade 1 around 1918). Notably, Korean ST5 isolates formed a sublineage distinct from North American strains, characterized by unique AMR profiles and divergence in the 1960s. ST72 formed an independent clade that was phylogenetically closer to clade 4 (ST1/ST188) than to the canonical CC8 group (clade 5). Furthermore, the ST1 isolates showed a temporal split into an older lineage and a recent sublineage, with expanded AMR pro-files. Conclusions: By integrating time-scale phylogenetics with cgMLST, we elucidated the evolutionary history and transmission dynamics of Korean MRSA.

Comparative Genomic and Epidemiologic Analysis of Methicillin-Resistant Staphylococcus aureus Isolates in Republic of Korea

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Abstract

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