Molecular Epidemiology and Virulence Gene Analysis of Methicillin-Resistant Staphylococcus aureus Associated with Skin and Soft Tissue Infections in the Shaoxing Region.

Objective: This study aimed to investigate the prevalence, molecular types, and virulence genes of methicillin-resistant Staphylococcus aureus (MRSA) causing skin and soft tissue infections (SSTIs) in the Shaoxing region.

Methods: MRSA strains were collected from patients with SSTIs in Shaoxing People's Hospital from January 2019 to December 2019. We conducted SCCmec typing, Staphylococcus protein A (SPA) typing, multilocus sequence typing (MLST), and virulence gene analysis using whole-genome sequencing on all MRSA strains.

Results: The detection rate of community-acquired MRSA (CA-MRSA) isolated from SSTI patients in our hospital was 33.3% (6/18). The primary SCCmec types of CA-MRSA strains were IV and V, with IVg(2B) and V(5C2&5) accounting for 16.7% each. Hospital-acquired MRSA (HA-MRSA) strains primarily exhibited SCCmec types IVa(2B) (25.0%), followed by II(2A) (16.7%), V(5C2) (16.7%), and V(5C2&5) (8.3%). SPA typing indicated that CA-MRSA strains causing SSTIs were predominantly t437 (14.3%), t034 (14.3%), t309 (14.3%), t4549 (14.3%), and t7637 (14.3%). The primary SPA type of HA-MRSA strains was t311 (16.7%). MLST typing revealed that the main sequence types (STs) of CA-MRSA strains causing SSTIs were ST22 (33.3%), followed by ST398, ST59, ST88, and ST630, each accounting for 16.7%. The principal STs of HA-MRSA strains were ST398 (16.7%), ST59 (16.7%), ST88 (16.7%), and ST5 (16.7%), followed by ST22, ST630, ST6, and ST188, each at 8.3%. The primary clones of CA-MRSA strains causing SSTIs were ST59-t437-IVg(2B) (16.7%) and ST630-t4549-V(5C2&5) (16.7%), while the primary clones of HA-MRSA strains were ST59-t437-IVa(2B), ST630-t4549-V(5C2&5), ST6-t304-IVa(2B), ST5-t311-II(2A), ST59-t172-IVa(2B), ST398-t571-V(5C2), ST398-t034-V(5C2), and ST5-t311-II(2A), each accounting for 8.3%. The detection rate of the lukSF-PV virulence gene was higher in CA-MRSA strains (50.0%) than in HA-MRSA strains (16.7%).

Conclusions: The isolation rate of CA-MRSA strains causing SSTIs was high in Shaoxing People's Hospital, with ST59-t437-IVg(2B) and ST630-t4549-V(5C2&5) being the predominant clones. MRSA strains exhibited multiple virulence genes, with the lukSF-PV gene having a higher detection rate in CA-MRSA strains, signifying its importance as a virulence factor in CA-MRSA.