Molecular characteristics and virulence gene profiles of Staphylococcus aureus isolates in Hainan, China

Abstract Background: There have been no reports regarding the molecular characteristics, virulence features, and antibiotic resistance profiles of Staphylococcus aureus (S. aureus) from Hainan, the southernmost province of China. Methods: 227 S. aureus isolates, consisting of 76 methicillin-resistant S. aureus (MRSA) and 151 methicillin-susceptible S. aureus (MSSA), were collected in 2013-2014 and 2018-2019 in Hainan, and investigated for their molecular characteristics, virulence genes, and antibiotic resistance profiles. Results: Thirty-four sequence types (STs) and 79 spa types were identified based on multilocus sequence typing (MLST) and spa typing, respectively. ST398 (14.1%, 32/227) was found to be the most prevalent, and moreover, the prevalence of ST398-MSSA increased significantly from 2013-2014 (5.5%, 5/91) to 2018-2019 (18.4%, 25/136). Seventy-six MRSA isolates were subject to staphylococcus chromosomal cassette mec (SCCmec) typing. SCCmec-IVa was the predominant SCCmec type, and specifically ST45-SCCmec IVa, an infrequent type in mainland China, was predominant in S. aureus from Hainan. Eleven virulence genes, including the Panton-Valentine leukocidin (pvl) and eta, were determined, and the positive rates of eta and pvl were found to be 57.3% and 47.6%. Such high prevalence has never been seen in mainland China before.