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目的 揭示结核分枝杆菌(Mycobacterium tuberculosis,MTB)北京基因型菌株的进化路径,在进化过程中产生的各个进化分支,以及每个分支的北京基因型菌株在人群中的流行情况.方法 收集2014年1月至2016年4月天津地区临床分离的567株MTB菌株,首先采用多重PCR试验分析菌株基因组中差异片段207(RD207)的缺失情况,以鉴定收集的菌株是否为北京基因型;然后分析所有的北京基因型MTB菌株基因组中差异区域RD105、RD181、RD150和RD142的缺失情况,以及菌株基因组NTF(noise transfer function)区中插入序列6110(IS6110)的存在情况.结果 567株临床分离的MTB菌株中,517株(91.2％)为北京基因型菌株.所有北京基因型菌株中,447株(86.5％)为NTF区含有IS6110的北京基因型现代株;70株(13.5％)为NTF区不含IS6110的北京基因型古代株.基于大片段的多态性分析,北京基因型菌株被分为5个亚型,其中RD181(+)的北京基因型菌株为22株(4.3％),且全部为北京基因型古代株.RD181(-)/RD150(+)和RD181(-)/RD150(-)的北京基因型古代株分别为41株(7.9％)和7株(1.4％).447株现代菌株中,RD181(-)/RD150(+)和RD181(-)/RD150(-)的分别为404株(78.1％)和43株(8.3％).结论 MTB北京基因型中的现代株是天津地区的主要流行株;北京基因型MTB在人群传播流行中已经进化出5个分支,其中RD181(-)/RD150(+)的北京基因型现代株为主要的流行分支.“,”Objective To clarify the evolutionary pathway of Beijing genotype of Mycobacterium tuberculosis (MTB) and to elucidate the sublineages of Beijing strains.Methods The Beijing genotype isolates were identified from the 567 MTB isolates,which collected from the patients with pulmonary tuberculosis from Jan.2014 to Apr.2016 in Tianjin,China,by analyzing the deletion of regions of difference 207 (RD207).Large sequence polymorphism (LSP) of the Beijing strains were determined based on the presence or absence of RD105,RD181,RD150 and RD142.The insertion sequence 6110 (IS6110) insertion in noise transfer function (NTF) region was also analyzed.Results Of the 567 clinical isolates,517 (91.2％) were identified as Beijing genotype.Among these Beijing strains,447 (86.5％) belonged to modern Beijing strains that possessed IS6110 insertion in NTF region,whereas 70 (13.5％) belonged to ancient Beijing strains that had no IS6110 insertion in NTF region.Based on the LSP analysis,all 517 Beijing strains were further divided into five sublineages.22 (4.3％) were RD181 (+),and all these RD181(+) strains belonged to ancient Beijing genotype.41 (7.9％) and 7 (1.4％) were RD181(-)/RD150(+)and RD181(-)/RD150(-) ancient Beijing strain,respectively.Of the 447 modern Beijing strains,there were 404 RD181(-)/RD150(+) and 43 RD181(-)/RD150(-) strains,accounting for 78.1％ and 8.3％ of the Beijing isolates,respectively.Conclusion Modern Beijing strains are the most predominant in Tianjin,China.Based on the LSP analysis,the Beijing genotype strains have evolved five sublineages and the majority of isolates is the RD181(-)/RD150 (+) modern sublineage.