2022年北京市通州区一起霍乱疫情分离菌株的病原学特征分析

Etiological characteristics of a cholera epidemic in Tongzhou district,Beijing,2022

目的分析2022年北京市通州区一起霍乱弧菌引起的疫情的病原学特征,并与引起通州区过往疫情的菌株进行比对分析。方法用实时荧光PCR方法检测样本中O1/O139群霍乱弧菌的特异性基因,同时按常规法对样本进行菌株的分离培养鉴定;用普通PCR方法检测霍乱弧菌的11种毒力基因;用微量肉汤稀释法进行12种药物的敏感性试验,采用NotⅠ限制性内切酶进行脉冲场凝胶电泳(PFGE)和聚类分析,基于全基因组序列进行菌株遗传学分析。结果本次疫情共检出5株O1群小川型非产毒霍乱弧菌,所有菌株均携带ompU、toxR、tcpI、tcpA^(EL)、hlyA^(EL)、hlyA^(CL)和rtxC基因,不携带ctxAB基因,5株菌耐药情况一致,均为美罗培南–头孢噻肟–头孢他啶–链霉素–氨苄西林–氨苄西林/舒巴坦6种药物耐药,为多重耐药菌株。PFGE分6种带型Ⅰ~Ⅵ,本次疫情菌株带型为Ⅱ型。与通州区既往检出的菌株相比,与2011年2株产毒O1群小川型霍乱弧菌带型较为接近,耐药情况一致,毒力基因携带情况有所差异,但都携带tcpA^(EL)基因。遗传学分析显示本次疫情菌株为不同于第七次世界大流行菌株的新出现的克隆群。结论通州区流行的O1群霍乱菌株以多重耐药小川型非产毒株为主,PFGE带型分散,本次疫情菌株是新出现的克隆群,以后的霍乱防控工作中应重视此类菌株并制定相应的策略。

Objective To analyze the etiological characteristics of a cholera epidemic in Tongzhou district of Beijing in 2022 and make a comparison with previous cholera epidemics in Tongzhou.Methods The specific genes of Vibrio cholerae O1/O139 were detected by real-time PCR.At the same time,the strains were isolated,cultured and identified by conventional method.Eleven virulence genes of V.cholerae were detected by common PCR,and 12 kinds of drug sensitivity tests were carried out by minimal inhibitory concentration method.NotⅠrestriction enzymes were used for pulsed field gel electrophoresis(PFGE)analysis and cluster analysis.Genetic analysis on strains was performed by whole genome sequencing.Results A total of 5 strains of non-virulence V.cholerae O1 serotype Ogawa were detected in this epidemic.All the strains carried ompU,toxR,tcpI,tcpA^(EL),hlyA^(EL),hlyA^(CL) and rtxC genes,but carried no ctxAB gene.The drug resistance of the 5 strains was consistent.All the strains were resistant to meropenem,cefotaxime,ceftazidime,streptomycin,ampicillin,and ampicillin/sulbactam.PFGE divided the strains into 6 types(Ⅰ–Ⅵ),and the strains causing this epidemic belonged to typeⅡ.The comparison with the two strains of virulence V.cholerae O1 serotype Ogawa detected in previous local epidemic in 2011 indicated the similar PFGE pattern,the drug resistance was same,the virulence gene carriage was different,but both carried tcpA^(EL) gene.Genetic analysis showed that the strains in this epidemic belonged to new and emerging clonal group which was different from the strain causing the 7th pandemic.Conclusion The predominant V.cholerae O1 strain in Tongzhou belonged to serotype Ogawa without toxin producing.PFGE patterns varied.The strains detected in this epidemic belonged to a newly emerged clone group.In cholera prevention and control in the future,attention should be paid to these strains and targeted strategies should be developed.