Clade 8 and Clade 6 Strains of Escherichia coli O157:H7 from Cattle in Argentina have Hypervirulent-Like Phenotypes
Clade 8 and Clade 6 Strains of Escherichia coli O157:H7 from Cattle in Argentina have Hypervirulent-Like Phenotypes
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DOI：
10.1371/journal.pone.0127710
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发表时间：
2015-06-01
期刊：
影响因子：
3.7
通讯作者：
Cataldi, Angel
中科院分区：
文献类型：
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作者：
Amigo, Natalia;Mercado, Elsa;Cataldi, Angel
溶血性尿毒综合征（HUS）是一种主要影响5岁以下儿童的疾病，其主要病原体是肠出血性大肠杆菌（EHEC）O 157：H7。阿根廷是世界上HUS发病率最高的国家。牛是大肠杆菌的主要宿主和感染源。coli O157：H7。到目前为止，对导致其流行的流行病学因素知之甚少。单核苷酸多态性（SNP）分型有助于确定9个E。大肠杆菌O 157：H7分支和8分支菌株与大多数重症病例相关。在这项研究中，8个随机选择的分离株肠出血性大肠杆菌O 157：H7从牛在阿根廷进行了研究，以及两个人的分离株。其中4个通过23个SNP的筛选被分类为进化枝8;两个人分离株也被分组在该进化枝中，而两个菌株与代表进化枝6的菌株密切相关。为了评估这些菌株的致病性，我们测定了毒力的相关性。通过ELISA试剂盒测定滋贺毒素产生。四株高产菌株，其中一株属于一种新的基因型，在培养的细胞中表现出高verocytotoxic活性。此外，这些进化枝8和6菌株显示出高RBC溶解和对上皮细胞的粘附。其中一株分支6菌株对正常吸水的抑制作用强于E. coliO 157：H7 EDL 933中的表达。此外，在小鼠模型中，显示高水平Stx 2产生和RBC裂解活性的菌株中的两种与致死性和尿毒症相关。因此，这种菌株在牛中的传播可能部分导致阿根廷HUS的高发病率。
The hemolytic uremic syndrome (HUS) whose main causative agent is enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a disease that mainly affects children under 5 years of age. Argentina is the country with the highest incidence of HUS in the world. Cattle are a major reservoir and source of infection with E. coli O157:H7. To date, the epidemiological factors that contribute to its prevalence are poorly understood. Single nucleotide polymorphism (SNP) typing has helped to define nine E. coli O157:H7 clades and the clade 8 strains were associated with most of the cases of severe disease. In this study, eight randomly selected isolates of EHEC O157:H7 from cattle in Argentina were studied as well as two human isolates. Four of them were classified as clade 8 through the screening for 23 SNPs; the two human isolates grouped in this clade as well, while two strains were closely related to strains representing clade 6. To assess the pathogenicity of these strains, we assayed correlates of virulence. Shiga toxin production was determined by an ELISA kit. Four strains were high producers and one of these strains that belonged to a novel genotype showed high verocytotoxic activity in cultured cells. Also, these clade 8 and 6 strains showed high RBC lysis and adherence to epithelial cells. One of the clade 6 strains showed stronger inhibition of normal water absorption than E. coli O157:H7 EDL933 in human colonic explants. In addition, two of the strains showing high levels of Stx2 production and RBC lysis activity were associated with lethality and uremia in a mouse model. Consequently, circulation of such strains in cattle may partially contribute to the high incidence of HUS in Argentina.