Antibiotic resistance and epidemiology of Staphylococcus aureus causing bloodstream infections

OBJECTIVE To isolate Staphylococcus aureus strains from blood samples of patients in Xinhua Hospital affiliated to Shanghai Jiaotong University School of Medicine during 2011 to 2019.Antibiotic resistance and epidemiology of the strains were analyzed. METHODS The antibiotic resistance of S. aureus isolated from blood culture during 10 years were analyzed by Whonet 5.6 software, and the detection rate of MRSA in adults and children were calculated. Some strains collected in the past 10 years were selected for DNA extraction and MLST analysis to understand the epidemic trend of S. aureus in our hospital. RESULTS A total of 320 strains of S. aureus were isolated from blood culture specimens in the past ten years, of which 35.0% were isolated from children and 65.0% were from adults. The overall detection rate of MRSA was 47.5%, and the detection rate of children isolates was 45.5%, the detection rate of adult isolates was 48.5%. Among them, 250 strains of S. aureus were selected for MLST typing. The main type of MRSA was ST5（35.4%）, The main type of MSSA strains was ST188（16.7%）, ST59（17.9%） was the children isolates and ST5（26.2%） was the adults isolates. CONCLUSION There are differences in antibiotic resistance of S. aureus between strains isolated from adults and children. The detection rate of MRSA in adults is slightly higher than that in children. The main ST type is also significantly different, suggesting empirical anti-infective therapy and nosocomial infection control for different populations should be performed.