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Abstract：
Shiga toxin-producing Escherichia coli (STEC) is an important food-borne pathogen, which can cause diseases such as diarrhea, hemorrhagic enteritis, and hemolytic uremic syndrome in humans. Twelve STEC isolates were collected from beeves and feces of commercial animals in China between 2019 and 2020 for this study. In addition to the determination of serotype and Shiga toxin subtype, whole-genome sequencing (WGS) was used for determining phylogenetic relationships, antimicrobial resistance (AMR), virulence genes, and sequence type (ST) of isolates. A total of 27 AMR genes were detected, and each STEC isolate carried more than 10 AMR genes. Eight STEC isolates from ground beef and four STEC isolated from feces were screened. A total of seven serotypes were identified, and one isolate ONT:H10 was undetermined by SeroTypeFinder. Three O157:H7 strains were confirmed and the remaining five serogroups were confirmed as O26:H11, O81:H31, O105:H8, O178:H19, and O136:H12. The phylogenetic analysis showed that STEC isolates of the same serotype or ST were clustered together based on cgMLST. The comparison of the genomes of 157 STEC reference isolates worldwide with our local STEC isolates showed that STEC isolates screened in China represented various collections and could not form a separate cluster but were interspersed among the STEC reference collection, which suggested that several STEC isolates shared a common ancestor irrespective of STEC serotype isolates. cgMLST revealed that isolates of the same O serotype clustered irrespective of their H type. Further investigation is required to determine the pathogenic potential of other serotypes of STEC, particularly in regard to these rare serotypes.
摘要：
产志贺毒素大肠杆菌(STEC)是一种重要的食源性致病菌,会导致腹泻等疾病，出血性肠炎,和溶血性尿毒综合征。在2019年至2020年期间，从中国商业动物的蜜蜂和粪便中收集了12株STEC分离株，用于本研究。除血清型和志贺毒素亚型的测定外，全基因组测序(WGS)用于确定系统发育关系，抗菌素耐药性（AMR），毒力基因，和分离物的序列类型(ST)。共检测到27个AMR基因，每个STEC分离物携带超过10个AMR基因。筛选了来自碎牛肉的八个STEC分离物和从粪便中分离的四个STEC。共鉴定出7种血清型,和一个分离物ONT:H10未通过SeroTypeFinder确定。确认了三个O157：H7菌株，其余五个血清群分别为O26：H11，O81：H31，O105：H8，O178：H19和O136：H12。系统发育分析表明，基于cgMLST，相同血清型或ST的STEC分离株聚集在一起。对全球157株STEC参考分离株的基因组与我们当地的STEC分离株的比较表明，在中国筛选的STEC分离株代表了各种集合，不能形成单独的簇，而是散布在STEC参考集合中，这表明几个STEC分离株共享一个共同的祖先，而与STEC血清型分离株无关。cgMLST显示，相同O血清型的分离株聚集在一起，而与H型无关。需要进一步调查以确定STEC其他血清型的致病潜力，特别是关于这些罕见的血清型。
