北京地区孕晚期妇女B族链球菌氟喹诺酮类耐药机制研究

Resistance mechanism on group B Streptococcus to Fluoroquinolone resistance isolated from late pregnancy women in Beijing

目的调查北京地区孕晚期(late pregnancy)妇女B族链球菌(group B Streptococcus,GBS)定植菌对氟喹诺酮类抗生素的耐药机制,为GBS的防控提供依据。方法常规采集来自首都医科大学附属北京地坛医院产科门诊产检的孕晚期妇女肛直肠与阴道下1/3分泌物进行GBS培养;氟喹诺酮类耐药以左氧氟沙星作为判定标准,调查本地区孕晚期妇女GBS对氟喹诺酮类耐药率;并研究氟喹诺酮耐药决定区(quinolone resistance-determining regions,QRDRs)gyrA与parC基因突变位点,探讨其与血清型的关系。结果共收集孕晚期妇女定植GBS菌株674株,经培养鉴定GBS阳性菌株66株,其中左氧氟沙星耐药21株(31.8%)。血清分型主要为III型,占57.1%(12/21);其次为Ib型,占42.9%(9/21)。QRDRs gyrA基因为Ser-81-Leu突变(100.0%,21/21)。parC基因主要为Ser-79-Phe或Tyr的单位点突变(47.6%,10/21);其次为Ile-218-Thr与Ile-219-Phe双位点突变(19.0%,4/21),且均为血清III型。结论北京地区孕晚期妇女GBS定植菌株对氟喹诺酮类抗生素耐药形势较为严峻,其耐药机制既有共同特征,亦呈现一定的地区分布特征。

Objective To investigate the mechanism of group B Streptococcus(GBS)to fluoroquinolone resistance colonized in late pregnancy women in Beijing,and to provide related evidence in prevention and control of GBS.Methods The secretions from the rectum and the lower third of the vagina were collected routinely for GBS cultures from late pregnancy women in the obstetrics outpatient department of our hospital.Levofloxacin was used as the criterion for determining fluoroquinolones resistance,and the fluoroquinolone resistance rate of GBS in late pregnancy women was investigated.Furthermore,the mutation sites of gyrA and parC gene in quinolone resistance-determining regions(QRDRs)were detected,and the relationship between them and serotypes were analyzed.Results A total of 674 GBS strains colonized in late pregnancy women were collected,66 were GBS-positive by the cultures.Among which,21 isolates(31.8%)were resistant to levofloxacin.The serotype was mainly type III,accounting for 57.1%(12/21);followed by type Ib,accounting for 42.9%(9/21).The mutation in gyrA gene was mainly Ser-81-Leu(100%,21/21),and in parC gene was mainly Ser-79-Phe or Tyr single-site mutation(47.6%,10/21),followed by Ile-218-Thr and Ile-219-Phe double-site mutations(19.0%,4/21),which belonged to serotype III.Conclusion High prevalence of fluoroquinolone resistance of GBS colonized in late pregnancy women was observed in Beijing.Not only the common features were found in resistance mechanism,but also the related geographical characteristics were involved.