Molecular Typing and Drug Resistance of Methicillin-Resistant Staphylococcus aureus in Skin and Soft Tissue Infections in Shaoxing.

Staphylococcus aureus, commonly colonizing the mucous membranes and skin of humans, is a prevalent pathogen responsible for Skin and Soft Tissue Infections (SSTIs), with a notably high prevalence of methicillin-resistant Staphylococcus aureus (MRSA). The antimicrobial resistance profiles of MRSA vary across different regions, with differences in population structure and epidemiological characteristics over time and geography. Molecular typing is frequently employed to investigate the population structure and transmission features among strains. The purpose of this study is to investigate the molecular epidemiological characteristics, virulence genes, and drug resistance of MRSA isolated from patients with skin and soft tissue infections in the Shaoxing region. Seventy-seven MRSA strains isolated from patients with SSTIs in the Shaoxing area from 2017 to 2022 were subjected to drug sensitivity testing using the VITEK 2 Compact fully automated system. The study utilized next-generation sequencing to conduct Staphylococcal Chromosome Cassette mec (SCCmec) typing, Staphylococcal Protein A (SPA) typing, Multilocus Sequence Typing (MLST), and investigate virulence genes in MRSA strains. The variations in antimicrobial resistance, virulence genes, and molecular typing among different genders and age groups were analyzed. The findings revealed that the resistance rate of MRSA to penicillin was 100%, while it was 61.04% for erythromycin and 59.74% for clindamycin. The resistance rate to other antibiotics was below 20%. MLST typing is mainly dominated by ST59 (22.08%) and ST398 (18.18%), while SCCmec typing is predominantly represented by IV (38 strains) and V (27 strains). SPA typing is mainly characterized by t437 (19.48%) and t34 (14.29%). The major clones of SSTIs in the Shaoxing area are ST59-t437-IV and ST398-t34-V. The strains carry 17 enterotoxin genes, with the highest detection rates found in sek and seq (32.47%), PVL (12.99%), and tst (7.79%).This study demonstrates that skin and soft tissue infections in the Shaoxing region are caused mainly by ST59-t437-IV and ST398-t34-V strains, which carry multiple virulence genes. PVL is identified as a significant virulence factor in MRSA strains.