2018—2022年北京市某区腹泻病例中致泻性大肠埃希菌的感染和分子分型特征分析

Analysis of the infection and molecular characteristics of diarrheagenic Escherichia coli in a specific district of Beijing City,2018—2022

目的了解北京市某区腹泻病例中致泻性大肠埃希菌(DEC)的感染情况和分子分型特征,为进一步防控工作提供依据。方法2018—2022年从北京市某区3家监测哨点医院采集1600例腹泻病例粪便标本,分离标本中的DEC;采用多重PCR技术检测其毒力基因得到致病型,结合流行病学和临床资料进行分析。同时应用脉冲电场凝胶电泳(PFGE)技术得到分子分型,并将ETEC、EPEC和EAEC型菌株图谱作聚类分析。结果2018—2022年北京市某区1600份标本中有144份标本分离到DEC,检出率为9.00%(144/1600)。菌株致病型以ETEC为主,其次依次为EPEC、EAEC、EHEC,未检出EIEC。DEC感染病例男女比例为1.48∶1,31~45岁年龄组的DEC检出率最高(11.15%,59/529)。DEC阳性检出率最高的年份为2019年,各年夏季检出率均最高。DEC在不同年龄组和年份中的阳性检出率均有显著差异。DEC阳性病例症状以腹泻、脱水、腹痛为主,且多为水样便。144株DEC分为111条带型,同源性13.07%~100.00%。同带型的菌株数目2~7条,分离时间间隔从当天到几年不等。结论本区DEC致病型以ETEC和EPEC为主,且存在EHEC感染;夏季高发,青壮年中检出较多;PFGE条带呈高度多态性分布。

Objective To comprehend the epidemiological and molecular characteristics of diarrheagenic Escherichia coli(DEC)in a specific district of Beijing City from 2018 to 2022,aiming to provide evidence for the prevention and control of related diseases.Methods Stool specimens of 1600 diarrhea cases were collected from 3 surveillance sentinel hospitals in one district of Beijing from 2018 to 2022,and DEC strains were isolated from the specimens.The virulence genes were detected by multiplex PCR,and the pathogenic types were obtained.The epidemiological and clinical data were analyzed.Simultaneously,pulsed-field gel electrophoresis(PFGE)was used to ascertain the molecular types of the strains.Cluster analysis was performed on the fingerprints of ETEC,EPEC,and EAEC strains.Results DEC strains were isolated in 144 of 1600 specimens from one district of Beijing from 2018 to 2022,with a detection rate of 9.00%(144/1600).The primary pathogenic type was ETEC,followed by EPEC,EAEC,and EHEC,no EIEC cases were detected.The male-to-female ratio of DEC infection cases was 1.48∶1,with the highest detection rate occurring in the 31~45 age group(11.15%,59/529).The year 2019 exhibited the highest positive detection rate of DEC,with the highest rates consistently observed during the summer months.Significant differences in the positive detection rate of DEC were observed among different age groups and years.Most of the DEC-positive patients suffered diarrhea,dehydration,abdominal pain and watery stool.The 144 DEC strains yielded 111 bands,with homology ranging from 13.07%to 100.00%.Isolates of the same type ranged from 2 to 7 strains,and their separation intervals varied from the same day to several years.Conclusion ETEC and EPEC were the predominant pathogenic types of DEC in this area,while EHEC infections persisted.DEC exhibited a high incidence during the summer and was more frequently detected in young adults.The PFGE bands exhibited a highly polymorphic distribution.