2013年湖南省一起B群流脑聚集性疫情菌株分子分型分析

目的了解湖南湘西地区B群流脑聚集性疫情中病例及其密切接触人群中分离到的B群脑膜炎奈瑟菌的分子分型特征及其流行关系。方法对病例的血液标本及其密切接触者的咽拭子标本进行分离、培养及生化鉴定,确认为脑膜炎奈瑟菌后,对菌株进行血清学分群和药敏试验;采用多位点序列分型(multilocus sequence typing,MLST)以及脉冲场凝胶电泳(pulsed-field gel electrophoresis,PFGE)方法对菌株进行分子分型。结果共分离到3株B群脑膜炎奈瑟菌,均对复方磺胺甲恶唑(SXT)耐药,对青霉素(PEN)和氨苄青霉素(AMP)的药敏结果为中介度,对其他9种抗生素米诺环素(MIN)、头孢曲松(CRO)、头孢噻肟(CTX)、利福平(RIF)、阿奇霉素(AZM)、氯霉素(CHL)、环丙沙星(CIP)、左氧氟沙星(LVX)和美洛培南(MEM)均敏感,PFGE结果显示3株菌株为同一带型,MLST结果显示3株菌株均为ST-4821 complex高致病克隆群。结论该起湖南湘西地区B群流脑聚集性疫情中病人与其密切接触者中分离到的B群脑膜炎奈瑟菌在分子分型实验中呈现高度一致性,提示为同一来源。流脑菌在湖南省的菌群已经发生变迁,带致病性克隆群的B群菌株可能成为优势菌株,引起流脑的暴发流行。

Analysis on molecular genotyping of Neisseria meningitidis serogroup B strains isolated in an aggregatation epidemic of epidemic cerebrospinal meningitis in Hunan Province

Objective To study the characteristics of molecular typing of Neisseria meningitidis serogroup B strains isolated in an aggregatation epidemic of epidemic cerebrospinal meningitis in Hunan Province and to explore the epidemiological correlation between the isolates from the cases and close contacts.Methods We collected blood specimens from the patients and throat swab specimens from the close contacts.Neisseria meningitidis was identified by isolation,culture and biochemical identification.Then the strains were subjected to serological grouping,drug susceptibility testing,and genotyping by multilocus sequence typing （MLST） and pulsed-field gel electrophoresis （PFGE）.Results Three Neisseria meningitidis serogroup B strains were isolated,and all of them were sensitive to minocycline （MIN）,ceftriaxone （CRO）,cefotaxime （CTX）,rifampicin （RIF）,azithromycin （AZM）,chloramphenicol （CHL）,ciprofloxacin （CIP）,levofloxacin （LVX） and meropenem （MEM）,moderately sensitive to penicillin （PEN） and ampicillin （AMP）,but resistant to sulfamethoxazole （SXT）.PFGE showed that the 3 strains belonged to the same banding pattern and MLST revealed that the strains were all ST-4821 complex group of highly pathogenic clones.Conclusions Neisseria meningitidis serogroup B strains isolated from the patients and the close contacts in the aggregatation epidemic of epidemic cerebrospinal meningitis in Hunan Province are all the same molecular type,and the high consistency of the results suggests that all of them are from the same source.Neisseria meningitidis strains have changed in Hunan Province; Neisseria meningitidis serogroup B strains with pathogenic genotype may become the dominant strains causing meningitts outbreaks.