妊娠35~37周女性定植B族链球菌的血清和多位点序列分型及其相互关系

Serum and multilocus sequence typing of group B streptococcus colonized in women at 35-37 weeks of pregnancy and their relationship

目的 探讨北京某妇产医院妊娠35~37周女性生殖道和消化道定植的B族链球菌(group B streptococcus,GBS)的血清分型、多位点序列分型(multilocus sequence typing,MLST)及其之间的关系,为临床防治GBS感染以及疫苗的研制提供参考依据。方法 妊娠35~37周女性常规进行阴道、直肠拭子联合采样,通过细菌培养、鉴定,分离GBS菌株,利用多重聚合酶链式反应(polymerase chain reaction,PCR)技术及第一代测序分别进行荚膜多糖血清分型和MLST分型,并通过统计学方法分析两种分型之间的关联性。结果 147名妊娠妇女定植GBS菌,其中共发现7种血清型,前三位分别是Ⅲ型占38.7%(57/147)、Ia型占35.3%(52/147)、Ib型占19.0%(28/147),另有2株未分型(non-typeable,NT)占1.4%(2/147);MLST分型共发现22种基因型,其中最主要的基因型是ST19占30.6%(45/147)、ST10占17.0%(25/147)、ST12占12.2%(18/147)、ST1占10.2%(15/147),另有3株菌为新发现的基因型占2.0%(3/147);GBS菌株主要血清型(Ia、Ib、Ⅲ)和MLST的主要分型(ST1、ST10、ST12、ST19)之间关联性存在统计学意义(χ^(2)=75.29,P<0.05),进一步计算了Pearson列联系数C=0.6。结论 本研究中,最常见3种血清型(Ⅲ型、Ⅰa型、Ⅰb型)覆盖了93.2%妊娠妇女定植的GBS(137/147),GBS荚膜多糖三价结合疫苗包含上述三种血清型,提示该疫苗应用可能减少本地区围生期妇女GBS定植。ST19/Ⅲ、ST10/Ia和ST12/Ia型是妊娠妇女定植的主要序列型/血清型,为研制有针对性的GBS疫苗提供参考依据。另外,多位点序列分型中新序列型的发现补充了B族链球菌MLST数据库。

Objective To discuss the serotyping,multilocus sequence typing(MLST)of group B streptococcus(GBS)colonized in reproductive tract of women at 35-37 weeks gestation in an Obstetrics and Gynecology Hospital of Beijing,and to provide reference for clinical prevention and treatment of GBS infection and research and development of vaccines.Methods Women at 35-37 weeks of gestation were routinely sampled with vaginal and rectal swabs.GBS strains were cultured,identified and isolated.Capsular polysaccharide serotyping and MLST typing were performed by multiplex polymerase chain reaction(PCR)and first generation sequencing,respectively,and the correlation between the two types was analyzed by statistical method.Results GBS strains were colonized in 147 pregnant women,of which 7 serotypes were found.The first three strains were 38.7%(57/147)of typeⅢ,35.3%(52/147)of type Ia,19.0%(28/147)of type Ib,and 1.4%(2/147)of non-typable(NT)strains.Twenty-two genotypes were found in MLST genotypes.The popular genotypes were ST1930.6%(45/147),ST1017.0%(25/147),ST1212.2%(18/147),ST110.2%(15/147)and 3 new genotypes 2.0%(3/147).The correlation between the main serotypes of GBS(Ia,Ib,Ⅲ)and the main types of MLST(ST19,ST10,ST12,ST1)was statistically significant(χ^(2)=75.29,P<0.05).The Pearson contingency coefficient was calculated further,C=0.6.Conclusion In this study,the three most common serotypes(Ⅲ,Ia and Ib)covered 93.2%of GBS colonized in pregnant women(137/147),and GBS capsular polysaccharide protein conjugate vaccines contained the above three serotypes,suggesting that the application of this vaccine may reduce GBS infection in perinatal women in this area.ST19/Ⅲ,ST10/Ia and ST12/Ia types are the main sequence types/serotypes that colonize pregnant women,which provide reference for developing targeted GBS vaccines.In addition,the discovery of new sequences in multilocus sequence typing supplements the MLST database of group B streptococcus.