河北省保定市一起人间布鲁菌病聚集性疫情分离菌株遗传学特征分析

Genetic characteristics of Brucella strains isolated from a human brucellosis epidemic in Baoding City of Hebei Province

目的:分析河北省保定市1起人间布鲁菌病(简称布病)聚集性疫情的流行病学和分离菌株遗传学特征,为布病疫情防控提供科学依据。方法:采用虎红平板凝集试验和试管凝集试验对2018年保定市1起人间布病疫情中的高危人群(n=22)进行布鲁菌抗体检测;对布病患者(n=3)血液进行培养,对分离出的菌株进行传统法鉴定,运用多位点可变数目串联重复序列分析(MLVA)和多位点序列分析(MLST)方法分析菌株的遗传学特征。结果:高危人群血清布鲁菌抗体阳性率为4.55%(1/22)。3名患者血培养均检出布鲁菌可疑菌株(菌株编号:BDY-1、BDY-2、BDY-3),并鉴定为羊种生物3型布鲁菌。MLVA结果显示,BDY-1与BDY-2菌株是同一基因型,BDY-3菌株在Bruce04和Bruce16位点分别增加了2个串联重复序列,在Bruce30位点少了3个串联重复序列,3株菌株panel 1(MLVA-8)基因型为42,panel 1+panel 2A(MLVA-11)基因型为116,均属于"东地中海组",且与羊种生物3型布鲁菌聚类最近。MLST分析显示,3株菌株均为ST8型。结论:该起疫情的病原菌是羊种生物3型布鲁菌。今后保定市布病防控工作应加强高危人群的健康教育和行为干预。

Objective To analyze the genetic characteristics of Brucella strains isolated from a human brucellosis epidemic in Baoding City of Hebei Province,and to provide scientific basis for control and prevention of brucellosis.Methods Brucella antibody was detected in a high-risk population(n=22)of brucellosis in Baoding City in 2018 by using rose bengal plate test and tube agglutination test.Blood samples of patients with brucellosis were collected for Brucella isolation(n=3).Conventional methods were used to identify the bacteria strains.Multiple locus variable-number tandem repeat analysis(MLVA)and multilocus sequence typing(MLST)were used to analyze the genetic characteristics of the strains.Results The sero-prevalence of Brucella antibodies in high-risk populations was 4.55%(1/22).Three suspected Brucella strains were isolated from blood samples of three patients(No.BDY-1,BDY-2 and BDY-3)and were identified as Brucella melitensis biovar 3.The results of MLVA showed that strain BDY-1 and strain BDY-2 were the same genotype.Strain BDY-3 added two tandem repeats at the locus of Bruce04 and Bruce16,respectively,and lost three tandem repeats at the locus of Bruce30.The genotype of panel 1(MLVA-8)and panel 1+panel 2A(MLVA-11)were 42 and 116,respectively,which belonged to the"East Mediterranean group".They were closely clustered with Brucella melitensis biovar 3.MLST analysis showed that all isolated strains could be classified into a ST8 type.Conclusions The isolated strains from the epidemic are Brucella melitensis biovar 3.In the future,the prevention and control of brucellosis in Baoding City should strengthen the health education and behavior intervention of the high-risk population.