科研动态

为了解我国不同地区屠宰生猪肉品中致泻性大肠杆菌污染情况及系统进化关系，降低由其带来的公共卫生危害，将近几年分离自华北、华东、华中及西南地区猪屠体表面的283株大肠杆菌进行了致泻性大肠杆菌多重PCR鉴定及2b-RAD测序分型。多重PCR鉴定结果显示，共检出36株致泻性大肠杆菌，检出率为12.7%，其中西南地区检出率（26.92%）高于华北（13.33%）、华东（10.57%）和华中（10.81%）地区；5种致泻类型中，产肠毒素大肠杆菌（ETEC）、肠致泻性大肠杆菌（EPEC）、肠聚集性大肠杆菌（EAEC）、肠出血性大肠杆菌（EHEC）和肠侵袭性大肠杆菌（EIEC）的占比分别为33.33%、30.56%、25.00%、5.56%和5.56%。将致泻性大肠杆菌进行2b-RAD测序，种群聚类分析显示，这36株致泻菌可分为8个亚群；系统发生树分析显示，亲缘关系较近菌株的致泻类型基本一致，分离时间也比较接近，而且来自同一地区菌株的亲缘关系相对较近。可见，我国屠宰生猪肉品中污染的致泻性大肠杆菌以ETEC、EPEC和EAEC类型为主，其流行分布有一定的地域差异，且其亲缘关系呈一定的时空特异性。本研究为精准防控生猪屠宰环节致泻性大肠杆菌污染，保障肉品卫生安全提供了科学数据和技术支撑。

Multiplex PCR Identification and 2b-RAD Sequence Analysis of Porcine Diarrheagenic Escherichia coli in Different Regions in China

In order to make clear the status of contamination and phylogenetic relationship of diarrheagenic Escherichia coli（E.coli）in raw pork products in different regions of China and to reduce the public health hazards that might occur therefrom，diarrheagenic E.coli strains were identified by multiplex PCR from 283 E.coli strains isolated from the surface of pig carcasses in North China，East China，Central China and Southwest China in recent years，then 2b-RAD sequencing and gene typing were carried out. It was found that，by multiplex PCR，36 strains of diarrheagenic E.coli were detected out，with the detection rate of 12.7%，among which，the detection rate in Southwest China（26.92%）was significantly higher than those in North China（13.33%），East China（10.57%）and Central China（10.81%）；for the five types of diarrhea，enterotoxigenic E.coli（ETEC），enteropathogenic E.coli（EPEC），enteroaggregative E.coli（EAEC），enterohemorrhagic E.coli（EHEC）and enteroinvasive E.coli（EIEC）accounted for 33.33%，30.56%，25.00%，5.56% and 5.56%，respectively. After 2b-RAD sequencing for species clustering analysis，it was found that the 36 strains could be classified into 8 subgroups；it was shown that，by phylogenetic tree analysis，the strains with close genetic relationship belonged to similar diarrheagenic types，and their isolation time was also close，in particular，the strains from the same region were with closely genetic relationship. It was concluded that the diarrheagenic E.coli contaminated in raw pork products mainly included three types of ETEC，EPEC and EAEC，the diarrheagenic E.coli strains were distributed with regional diversity，and their genetic relationships were with certain spatial and temporal specificity. In conclusion，some scientific data and technical support were provided to prevent and control the containment with diarrheagenic E.coli during the process of pig slaughtering and to safeguard hygiene and safety of pork products.

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