上海地区2015—2018年产毒性大肠埃希菌毒力基因及定植因子携带特征分析

Characteristic analysis on virulence genes and colonization factors of enterotoxigenic Escherichia coli in Shanghai from 2015 to 2018

【目的】分析上海地区2015—2018年产毒性大肠埃希菌(ETEC)毒力基因及定植因子(CF)的携带特征,为相关腹泻疾病防控及研究提供依据。【方法】采用多重荧光PCR的方法,对上海地区2015—2018年分离到的300株ETEC所携带的毒力基因(est,elt)及部分主要定植因子(CFA/I,CS1/PCFO71,CS2-8,CS12,CS14,CS17-19,CS21)进行检测,统计分析其在人群中的分布特征等。【结果】目标菌株中,57.00%(171/300)携带est基因,30.33%(91/300)携带elt基因,12.67%(38/300)同时携带est与elt基因;68.33%(205/300)的菌株根据所检测的14组定植因子可分为18种型别,其中最常出现的3种型别为13型(CS6,85/300),18型(CS21,65/300)和7型(CS2+CS3+CS21,17/300);出现频次最多的定植因子为CS21与CS6,其携带者在年龄分布上的差异有统计学意义,CS21携带者多为40岁及以下患者,而CS6多见于40岁以上的患者。【结论】上海地区2015—2018年检出的ETEC中est毒力基因比例较大;虽然不同年份间ETEC菌株携带的毒力基因和定植因子在构成上存在较大差异,但大多菌株携带的定植因子种类相对集中;其主要携带的定植因子为CS6(以elt为主)与CS21(均为est),并呈现出一定的年龄分布特征。

[Objective] To study the virulence genes and the colonization factors (CF) of enterotoxigenic Escherichia coli (ETEC) in Shanghai from 2015 to 2018,describe the feature and provide the evidence for the prevention and control or further research of the ETEC-related diarrhea.[Methods] The virulence genes ( est and elt ) and the major CFs (CFA/I,CS1/PCFO71,CS2-8,CS12,CS14,CS17-19,CS21) of 300 ETEC strains were collected and detected in Shanghai from 2015 to 2018 by multiplex real time PCR and the population distribution characteristics described by statistical analysis.[Results] In target strains,57.00%(171/300) carried est alone,and 30.33%( 91/300 ) carried elt alone,while 12.67%(38/300) carried both est and elt .And 68.33%(205/300) of the strains were typed to 18 combinations by 14 groups of CFs detected.Type 13 (CS6 alone,85/300),type 18 (CS21 alone,65/300) and type 7 (CS2+CS3+CS21,17/300) were the top three combinations.By counting the CFs separately in the combinations,the most common CFs were CS21 and CS6.The difference was statistically significant in age distribution among the patients from whom the ETEC carried CS21 or CS6.CS21 and CS6 was frequently found in patients below 40 and above 40 respectively.[Conclusion] Among the ETEC collected in Shanghai from 2015 to 2018,most of the strains carry est gene alone.Though the composition of the virulence genes and the CFs varied in different years,most of the strains carry some major CFs such as CS6 or CS21.The strains carried CS6 alone (mainly with elt ) or CS21 alone (all with est ) show statistically significant difference in age distribution of the patients.