Cumulative acquisition of pathogenicity islands has shaped virulence potential and contributed to the emergence of LEE-negative Shiga toxin-producing <i>Escherichia coli</i> strains

Shiga toxin-producing <i>Escherichia coli</i> (STEC) are foodborne pathogens causing severe gastroenteritis, which may lead to hemolytic uremic syndrome. The Locus of Enterocyte Effacement (LEE), a Pathogenicity Island (PAI), is a major determinant of intestinal epithelium attachment of a group of STEC strains; however, the virulence repertoire of STEC strains lacking LEE, has not been fully characterized. The incidence of LEE-negative STEC strains has increased in several countries, highlighting the relevance of their study. In order to gain insights into the basis for the emergence of LEE-negative STEC strains, we performed a large-scale genomic analysis of 367 strains isolated worldwide from humans, animals, food and the environment. We identified uncharacterized genomic islands, including two PAIs and one Integrative Conjugative Element. Additionally, the Locus of Adhesion and Autoaggregation (LAA) was the most prevalent PAI among LEE-negative strains and we found that it contributes to colonization of the mice intestine. Our comprehensive and rigorous comparative genomic and phylogenetic analyses suggest that the accumulative acquisition of PAIs has played an important, but currently unappreciated role, in the evolution of virulence in these strains. This study provides new knowledge on the pathogenicity of LEE-negative STEC strains and identifies molecular markers for their epidemiological surveillance.

产志贺毒素大肠埃希菌（Shiga toxin-producing Escherichia coli, STEC）是一类食源性致病菌，可引发重症胃肠炎，甚至进展为溶血性尿毒症综合征。肠细胞脱落位点（Locus of Enterocyte Effacement, LEE）作为一类致病岛（Pathogenicity Island, PAI），是部分STEC菌株黏附肠上皮细胞的核心致病决定因子；然而，缺失LEE的STEC菌株的毒力谱尚未得到充分解析。近年来多个国家中LEE阴性STEC菌株的检出率持续攀升，凸显了该类菌株研究的重要价值。为深入解析LEE阴性STEC菌株的出现机制与演化基础，本研究对全球范围内分离自人类、动物、食品及环境的367株菌株开展了大规模基因组分析。研究团队鉴定出多种尚未被表征的基因组岛，包括2个致病岛及1个整合接合元件（Integrative Conjugative Element）。此外，黏附与自聚集位点（Locus of Adhesion and Autoaggregation, LAA）是LEE阴性菌株中分布最为广泛的致病岛，且实验证实其可促进小鼠肠道定植。本研究通过全面严谨的比较基因组学与系统发育分析表明，致病岛的累积获取在该类菌株的毒力演化过程中发挥了此前未被学界重视的重要作用。本研究为LEE阴性STEC菌株的致病性研究提供了全新认知，并为其流行病学监测鉴定了特异性分子标志物。

搜集汇总

背景与挑战

背景概述

该数据集支持一项关于LEE阴性产志贺毒素大肠杆菌（STEC）菌株的研究，通过对全球367株菌株的基因组分析，揭示了致病岛的累积获得如何塑造毒力潜力并促进这些菌株的出现。研究特别关注LAA致病岛在肠道定植中的作用，为流行病学监测提供了新的分子标记。