Characterization and virulence clustering analysis of extraintestinal pathogenic Escherichia coli isolated from swine in China.
Characterization and virulence clustering analysis of extraintestinal pathogenic Escherichia coli isolated from swine in China.
复制标题
中国猪肠外致病性大肠埃希菌特征及毒力聚类分析
DOI：
10.1186/s12917-017-0975-x
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发表时间：
2017-04-08
影响因子：
2.6
通讯作者：
Yao H
中科院分区：
文献类型：
--
作者：
Zhu Y;Dong W;Ma J;Yuan L;Hejair HM;Pan Z;Liu G;Yao H
背景猪肠道外致病性大肠杆菌（ExPEC）是一种严重危害养猪业的重要病原菌，在我国也呈上升趋势。到目前为止，在ExPEC中已经认识到各种毒力因子。在这里，我们调查收集的菌株的毒力基因型和克隆结构，以提高知识的系统发育特征的猪ExPEC在China.ResultsWe分离64中国猪ExPEC菌株从2013年至14日在中国。多重PCR结果显示，B1、B2、A和D系统发育群的分布分别为9.4%、10.9%、57.8%和21.9%。PCR检测到19个毒力相关基因，其中ompA、fimH、vat、traT和iutA基因占优势。毒力相关基因在B2组中的检出率明显高于A、B1和D组，其中usp、cnf1、hlyD、papA和ibeA仅见于B2组。进行了基因分型分析，并确定了四个菌株群（命名为I至IV）。聚类IV包含来自组B2的所有分离株，并且聚类IV分离株在小鼠感染模型中具有最强的致病性。由于系统发育组B2和D ExPEC分离株通常被认为是毒性的，因此对这些分离株进行了多位点序列分型（MLST）分析，以进一步研究遗传关系。发现了两种新的序列类型，ST 5170和ST 5171。在我们的B2和D组分离物中鉴定的9个克隆复合物中，CC12和CC95已被指示具有高度的人畜共患病致病性。组B2和非B2菌株的毒力和基因型的区别符合MLST analysis.ConclusionThis研究揭示了显着的遗传多样性之间ExPEC菌株，有助于我们更好地了解其发病机制。重要的是，我们的数据表明，B2组（第四簇）菌株引起动物疾病的风险最高，并说明了基因型和毒力之间的相关性。
BackgroundSwine extraintestinal pathogenic Escherichia coli (ExPEC) is an important pathogen that leads to economic and welfare costs in the swine industry worldwide, and is occurring with increasing frequency in China. By far, various virulence factors have been recognized in ExPEC. Here, we investigated the virulence genotypes and clonal structure of collected strains to improve the knowledge of phylogenetic traits of porcine ExPECs in China.ResultsWe isolated 64 Chinese porcine ExPEC strains from 2013 to 14 in China. By multiplex PCR, the distribution of isolates belonging to phylogenetic groups B1, B2, A and D was 9.4%, 10.9%, 57.8% and 21.9%, respectively. Nineteen virulence-related genes were detected by PCR assay; ompA, fimH, vat, traT and iutA were highly prevalent. Virulence-related genes were remarkably more prevalent in group B2 than in groups A, B1 and D; notably, usp, cnf1, hlyD, papA and ibeA were only found in group B2 strains. Genotyping analysis was performed and four clusters of strains (named I to IV) were identified. Cluster IV contained all isolates from group B2 and Cluster IV isolates had the strongest pathogenicity in a mouse infection model. As phylogenetic group B2 and D ExPEC isolates are generally considered virulent, multilocus sequence typing (MLST) analysis was performed for these isolates to further investigate genetic relationships. Two novel sequence types, ST5170 and ST5171, were discovered. Among the nine clonal complexes identified among our group B2 and D isolates, CC12 and CC95 have been indicated to have high zoonotic pathogenicity. The distinction between group B2 and non-B2 isolates in virulence and genotype accorded with MLST analysis.ConclusionThis study reveals significant genetic diversity among ExPEC isolates and helps us to better understand their pathogenesis. Importantly, our data suggest group B2 (Cluster IV) strains have the highest risk of causing animal disease and illustrate the correlation between genotype and virulence.