Abstract: Objective To investigate the molecular epidemiological characteristics of human brucellosis in Alxa league, Inner Mongolia autonomous region (Inner Mongolia), China. Methods The clinical isolates of suspected Brucella with a positive blood culture result during 2015 to 2019 were identified by conventional biological methods and multiplex PCR assay. The molecular epidemiological characteristics of Brucella were investigated using multiple-locus variable-number tandem repeat analysis (MLVA). Results Twenty-three suspected Brucella strains were isolated from the confirmed cases of brucellosis in Alxa league from 2015 to 2019, and were identified as B. melitensis biovar 3 using conventional biological methods and multiplex PCR assay. Among the 23 cases, herdsmen accounted for 30.43% (7/23) and farmers accounted for 39.13% (9/23), both of whom had a history of sheep contact. The positive rate of Brucella antibody in serum was 78.26% (18/23). The MLVA showed that the 23 strains had genotypes of the main epidemic B. melitensis strains in China. According to the three loci with differences, the strains isolated from Bayanmuren Sumu belonged mainly to one group, and the two strains from Jilantai town belonged to another group. The 23 strains were associated with the isolates from Ningxia, Liaoning, Shandong, Zhejiang, Shanghai, and Guangdong (provinces, autonomous regions, and municipalities directly under the central government), and were not associated with isolates from its neighboring province Gansu. Conclusion The Brucella strains from Alxa league, Inner Mongolia are consistent with the epidemic strains of brucellosis in China, and are associated with the isolates from Ningxia, Liaoning, Shandong, Zhejiang, Shanghai, and Guangdong (provinces, autonomous regions, and municipalities directly under the central government).

Key words: Brucellosis, Epidemiological characteristics, Brucella, Genotype, Alxa league

摘要： 目的 研究内蒙古自治区（内蒙古）阿拉善盟地区人感染布鲁氏菌的分子流行病学特征。方法 对2015－2019年间血培养阳性的疑似布鲁氏菌，应用常规生物学和多重PCR方法鉴定临床分离菌株，应用多位点串联重复序列分析（MLVA）方法研究其分子流行病学特征。结果 2015－2019年间阿拉善盟地区布病确诊患者中分离到23株疑似布鲁氏菌，经常规生物学和多重PCR鉴定为羊种布鲁氏菌生物3型菌株。23例病例中牧民占30.43%（7/23），农民占39.13%（9/23），皆有羊接触史。血清布鲁氏菌抗体阳性率为78.26%（18/23）。MLVA分析表明23株菌株属于我国羊种布鲁氏菌主要流行菌株基因型，根据有差异的3个位点，分离自巴彦木仁苏木的菌株主要集中在一组内，来自吉兰泰镇的2株菌株集中在另一组内。23株布鲁氏菌分别与宁夏、辽宁、山东、浙江、上海、广东省（自治区、直辖市）分离菌株相关，而与其临近的甘肃省分离菌株无相关性。结论 内蒙古阿拉善盟地区布鲁氏菌菌株与我国的布病流行菌株一致，与宁夏、辽宁、山东、浙江、上海、广东省（自治区、直辖市）分离菌株相关。

关键词: 布鲁氏菌病, 流行病学特征, 布鲁氏菌, 基因分型, 阿拉善盟