Molecular and virulence characteristics of Staphylococcus aureus isolated from neonates / 中华微生物学和免疫学杂志

ABSTRACT

Objective:To analyze the molecular and virulence characteristics of Staphylococcus aureus ( S. aureus) isolated from neonates. Methods:A total of 189 S. aureus isolates were collected from Beijing Children′s Hospital from January 2013 to October 2019 and analyzed by multilocus sequence typing (MLST), staphylococcal cassette chromosome mec (SCC mec) typing and Spa typing. Panton-valentine leucocidin (PVL)-encoding gene ( pvl) and 21 superantigen virulence genes were also detected. Results:The 189 S. aureus strains were isolated from respiratory secretions ( n=125), pus ( n=55), blood ( n=8) and pleural effusion ( n=1). There were 98 methicillin-susceptible S. aureus (MSSA) belonging to 42 MSSA clones and 91 methicillin-resistant S. aureus (MRSA) belonging to 26 MRSA clones. ST188-t189 and ST59-SCC mecⅣa-t437 were the predominant MSSA and MRSA clones accounting for 11% and 53%, respectively. The prevalence of pvl gene in MRSA isolates was significantly higher than that in MSSA isolates (32% vs 10%, P<0.01). There were 166 isolates (88%) carrying at least one superantigen virulence gene and among the 21 genes, seq and seb were the most common genes accounting for 47% and 43%, respectively. The most common superantigen genotype was seb- sek- seq. The positive rates of superantigen genes in MRSA and MSSA isolates were 85% (77/91) and 90% (88/98), respectively ( P>0.05). Conclusions:The main clones of MRSA and MSSA were different in neonates. ST59-SCC mecⅣa-t437 was the most predominant MRSA clone, while ST188-t189 was the most predominant MSSA clone. MSSA clones were more dispersed. The prevalence of pvl gene in MRSA was higher than that in MSSA. No significant difference in the prevalence of superantigen genes was observed between MRSA and MSSA.