Molecular characterization of S. aureus isolates
We observed that of 70 S. aureus isolates, 11 were of S. argenteus , which is a novel staphylococcal species that is closely related to S. aureus genetically and has recently been defined as a part of the S. aureus complex (SAC) (23, 24). In this study, we identified S. argenteus using MLST analysis because the species cannot be distinguished from S. aureus through conventional microbiological identification methods. All S. argenteus isolates belonged to ST2250 with nontypable spa type, were methicillin susceptible, were mecA negative; however, one isolate carried the SCCmec type I structure.
Among 59 S. aureus isolates, we identified 12 STs. Specifically, ST239, ST45, and ST59 were predominant in methicillin-resistant S. aureus (MRSA) isolates, and ST15 and ST7 were predominant in methicillin-sensitive S. aureus (MSSA); ST45, ST59, and ST15 were dominant in blood culture. In addition, ST59, along with ST30 and ST239, was also frequently isolated from contaminated implant devices. ST8, ST15, ST30, and ST45 were more prevalent in AVG isolates than in TCC isolates. Furthermore, we assigned 25 spa types to the isolates, with t437, t4864, t1081, and t091 being the predominant spatypes. We observed ST8-t008 and ST239-t4864 in both MRSA and MSSA. Moreover, we analyzed the distribution of diverse STs and spatypes among various SCCmec types. ST5-SCCmec IV-t437 (abbreviated as ST5-IV-t437), ST59-V-t437, ST45-V-t081, and ST7-MSSA-t091 were the most prevalent clones in this study.