2017年—2020年北京市朝阳区健康人群携带脑膜炎奈瑟菌分子特征分析

Molecular characteristics of Neisseria meningitidis in healthy people in Chaoyang District,Beijing from 2017 to 2020

目的 对北京市朝阳区健康人群携带的脑膜炎奈瑟菌进行血清基因型和多位点序列分型研究,了解菌群病原学特征。方法 收集2017年—2020年北京市朝阳区健康人群咽拭子标本中分离的21株脑膜炎奈瑟菌,进行生化鉴定和种特异性基因复核,并采用real-time PCR方法进行血清基因分群,采用多位点序列分型方法对菌株进行分子分型,使用MEGA5.1软件构建系统进化树,分析分离株与全球高致病性克隆群的关系。结果 经鉴定21株菌均为脑膜炎奈瑟菌,血清群结果为B群11株,X群3株,不可分群7株。21株脑膜炎奈瑟菌共有16种序列型,其中14株属于4个已定义的克隆群,cc4821 (8株)、cc5(2株)、cc198(2株)、cc175 (2株),7株为无序列群,分别是ST-7962(2株)、ST-5586(3株)、ST-5613(1株)、ST-5863(1株)。基于管家基因序列的系统发生树,结果表明分离株ST型别多样化,存在全球高致病性克隆群cc4821和cc5,以B群cc4821为优势克隆。划为无序列群的2株B群的ST-7962分离株与cc4821关系较近,可能与B群分离株ST-4897(cc4821)存在局部进化。结论 2017年—2020年北京市朝阳区健康人群分离的脑膜炎奈瑟菌主要为B群,各年散在分布,且存在高致病性克隆,需加强关注脑膜炎奈瑟菌的菌群变迁,及早发现疫情,对公众的健康潜在危害应予以关注,并为免疫政策提供参考。

Objective This paper aims to study the serogenotype and multi-locus sequence typing of Neisseria meningitidis carried by healthy people in Chaoyang District,Beijing,and to understand the etiological characteristics of it.Methods Twen⁃ty-one strains of Neisseria meningitidis isolated from throat swab samples of healthy people from Chaoyang District of Beijing from 2017 to 2020 were collected for biochemical identification and species-specific gene review.Serum gene clustering was performed by real-time PCR,and molecular typing of the strains was performed by multi-locus sequence typing.MEGA5.1 software was used to construct phylogenetic tree to analyze the relationship between isolates and global highly pathogenic clones.Results All the 21 strains were identified as Neisseria meningitidis,including 11 strains of Group B,3 strains of group X and 7 strains of undifferentiated bacteria.The 21 strains of Neisseria meningitidis had a total of 16 types,among which 14 strains belonged to 4 defined clonal groups[cc4821(8 strains),cc5(2 strains),cc198(2 strains),cc175(2 strains)];7 strains were unsequenced groups[ST-7962(2 strains),ST-5586(3 strains),ST-5613(1 strain),and ST-5863(1 strain)].The phylogenetic tree based on housekeeper gene sequencing showed that the ST types of the isolates were diverse,and there were global highly pathogenic clusters(cc4821 and cc5),with group B cc4821 as the dominant clone.Two isolates of ST-7962 from Group B,classified as unsequenced group,were closely related to cc4821,which may have local evolution with ST-4897(cc4821)from Group B.Conclusion Neisseria meningitidis isolated from healthy people in Chaoyang District of Beijing from 2017 to 2020 is mainly consisted of Group B,which was dispersed in different years with highly pathogenic clones.There⁃fore,more attention should be paid to the evolution of Neisseria meningitidis.Early detection of the epidemic and the attention on the potential harm to public health should be performed,so as to provide reference for immunization policy.