ABSTRACT
@#Abstract: Objective To investigate the molecular characteristics and drug resistance of Staphylococcus aureus (SA) isolated from wounds of paatients with orthopedic trauma, and analyze the molecular subtyping, virulence genes and drug resistance of SA in wounds of patients, so as to provide reference for the prevention and treatment of wound SA infection in patients. Methods From January 2020 to June 2022, a total of 128 SA isolates were collected from wound specimens of orthopedic trauma patients at Wuxi 9th People's Hospital Affiliated to Soochow University. Methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible Staphylococcus aureus (MSSA) were differentiated using PCR. Multilocus Sequence Typing (MLST), staphylococcal protein A (spa), staphylococcal chromatoidal cassette mec (SCCmec), and accessory gene regulator (agr) typing were performed to determine the molecular typing and presence of virulence genes and drug resistance profiles. Results Among the 128 SA isolates, 76 (59.38%) were MRSA and 52 (40.62%) were MSSA. MRSA typing showed that, MLST was dominated by ST59 (46 strains, 60.53%), spa was dominated by t437 (52.63%), SCCmec was dominated by Ⅰ (42.11%) and Ⅳ (39.47%). MSSA typing showed that, MLST was dominated by ST188 (30.77%), spa was dominated by t189 (61.54%), agr was dominated by Ⅰ (53.85%). In MLST typing, ST59 of MRSA was higher than that of MSSA, and ST188 and ST6 of MRSA were lower than those of MSSA (χ2=36.207, 20.227, 9.984, P<0.05). In spa typing, the t437 of MRSA was higher than that of MSSA, and the t189 of MRSA was lower than that of MSSA (χ2=18.276, 32.781, P<0.05). The virulence genes showed that, the detection rates of hlb and seb in MRSA were higher than those in MSSA (χ2=47.838, 10.261, P<0.05), and the detection rates of cna and ebpS in MRSA were lower than those in MSSA (χ2=26.176, 8.305, P<0.05). Drug susceptibility test showed that, and the drug resistance rates of MRSA and MSSA to vancomycin (VAN) and linezolid (LNZ) were 0. The drug resistance rates of MRSA to oxacillin (OXA), ERY and CLI were 86.84%, 68.42% and 76.32%, which were higher than corresponding 7.69%, 42.31% and 46.15% of MSSA (χ2=78.055, 8.623, 12.200, P<0.05). The analysis of multi-drug resistant strains (MDR) showed that 76 MRSA strains were MDR strains, and 12 of 52 MSSA strains (23.08%) were MDR strains. Conclusions The molecular characteristics of SA isolated from orthopedic trauma patients' wounds were predominantly associated with MRSA strains of ST59-t437-SCCmec Ⅰ/Ⅳ-MRSA and ST188/ST6-t189-agr Ⅰ. These strains showed higher resistance to oxacillin, erythromycin, clindamycin, and higher susceptibility to vancomycin and linezolid. Such characteristics were closely related to the carriage of virulence genes. Clinicians should pay attention to the presence of MDR MSSA and develop appropriate antimicrobial strategies based on SA's molecular characteristics and antimicrobial resistance.