# Prevalence, Antimicrobial Resistance Profile, and Genetic Characteristics of Methicillin-Resistant Staphylococcus aureus Isolated from Retail Raw Fish in South Korea

## TL;DR

This study examines MRSA in raw fish from South Korea, revealing genetic diversity and potential local clustering, emphasizing the need for surveillance.

## Contribution

The study provides the first detailed genetic characterization of MRSA in retail raw fish in South Korea.

## Key findings

- MRSA strains showed distinct genetic profiles with two main clusters and a singleton strain.
- Four ST72-t324-SCCmecIVc strains from the same market shared identical resistance and virulence profiles.
- Potential local clustering of MRSA was observed in retail fish products.

## Abstract

Given the limited genetic characterization of methicillin-resistant Staphylococcus aureus (MRSA) in South Korea, we performed whole-genome sequencing (WGS) on eight MRSA strains isolated from raw fish products, including 327 sliced raw flatfish, 111 flatfish stew products, 85 sliced raw rockfish, and 11 rockfish stew products. Phylogenetic analysis revealed two distinct clusters—comprising five ST72-t324-SCCmecIVc strains and two novel sequence types—as well as a singleton strain (ST630-t4549-SCCmecV). A total of five antimicrobial resistance genes (ARGs), four plasmid replicon genes, three mobile genetic element genes, and seventy-three virulence factor genes were identified, with distinct genetic profiles observed between the clusters. Notably, several MRSA strains were isolated from samples obtained at the same retail market, indicating potential local clustering. Four ST72-t324-SCCmecIVc strains, collected from the same market, shared identical profiles in terms of four ARGs, two plasmid replicons, two mobile genetic elements, and several virulence factor genes. These findings provide valuable insights into the genomic characteristics of MRSA in raw fish products and highlight the need for ongoing surveillance and monitoring efforts in South Korea.