OBJECTIVE To understand the drug resistance, serotypes, virulence-associated genes and epidemiological characteristics of group B Streptococcus (GBS) isolated from puerpera in this area so as to provide bases for prevention of mother-to-infant infections.
METHODS Totally 67 strains of GBS were isolated from obstetrics outpatient department of The First Affiliated Hospital of Nanchang University from Jan. 2023 to Dec. 2023. The species of the strains were identified by VITEK MS, the drug susceptibility testing was carried out by disc diffusion method. Multilocus sequencing types, capsular types, virulence genes and drug resistance genes were analyzed by means of whole genome sequencing technique.
RESULTS The 67 strains of GBS were sensitive to penicillin, vancomycin, ceftriaxone and linezolid; the drug resistance rates to erythromycin and clindamycin were 76.12% and 55.22%, respectively. All strains fell into 7 serotypes, with serotype V predominant; 21 sequence types were involved, with ST529 most prevalent; 8 clonal complexes (CCs) were involved, with CC12 most common. Totally 17 types of drug resistance genes were identified, and the carrying rate of macrolide resistance gene ErmB was highest. Among all the virulence genes except for the adhesion genes fbsA and fbsB, the carrying rates of 18 genes involving in invasion, adhesion, and immune evasion-associated virulence genes were more than 86.57%; 67.16% of the strains co-expressed both PI-1 and PI-2a pilus islands.
CONCLUSIONS The drug resistance rate of the GBS strains isolated from the puerpera is high, and the strains carry multiple drug resistance genes and virulence genes and present with molecular clonal diversity. The serotype V/ST529 is the predominant clone, for which the prevention and control should be strengthened.
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