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首页> 外文期刊>Infection and immunity >Virulence of enterohemorrhagic Escherichia coli O91:H21 clinical isolates in an orally infected mouse model.
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Virulence of enterohemorrhagic Escherichia coli O91:H21 clinical isolates in an orally infected mouse model.

机译：口腔感染小鼠模型中肠出血性大肠杆菌O91：H21临床分离株的毒力。

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Escherichia coli K-12 strains producing high levels of Shiga-like toxin type II (SLT-II) but not SLT-I were previously shown to be virulent in an orally infected, streptomycin-treated mouse model. In this investigation, we tested the virulence of several SLT-II-producing enterohemorrhagic E. coli (EHEC) isolates from patients with hemorrhagic colitis or hemolytic uremic syndrome. All of the strains tested were able to colonize the mouse intestine. However, only two strains were consistently virulent for mice: O91:H21 strain B2F1 (Strr), which was previously shown to carry two copies of slt-II-related toxins, and O91:H21 strain H414-36/89 (Strr), which was found in this study to contain three genes from the slt-II group. The oral 50% lethal doses of strains B2F1 (Strr) and H414-36/89 (Strr) when fed to streptomycin-treated mice were less than 10 bacteria. Histological sections from moribund mice fed the O91:H21 strains demonstrated extensive renal tubular necrosis; however, hematological results were not consistent with a diagnosis of hemolytic uremic syndrome. The central role of SLT in the virulence of the O91:H21 EHEC strains was supported by the finding that streptomycin-treated mice preinoculated with monoclonal antibody specific for SLT-II survived oral challenge with either B2F1 (Strr) or H414-36/89 (Strr). The basis for the variation in virulence among the SLT-II-producing EHEC strains tested was not determined. However, a correlation between the capacity of an EHEC strain to grow in small intestinal mucus and lethality in the streptomycin-treated mice was observed.
机译：先前已证明在口腔感染链霉素治疗的小鼠模型中，大肠杆菌K-12菌株产生高水平的志贺样毒素II型（SLT-II），但不产生SLT-1。在这项调查中，我们测试了患有出血性结肠炎或溶血性尿毒症综合征的几株产生SLT-II的肠出血性大肠杆菌（EHEC）的毒力。所有测试的菌株都能够在小鼠肠道内定殖。但是，只有两种病毒株始终对小鼠具有毒性：O91：H21毒株B2F1（Strr），先前显示其携带slt-II相关毒素的两个拷贝，以及O91：H21毒株H414-36 / 89（Strr），在这项研究中发现它含有slt-II组的三个基因。当喂食链霉素治疗的小鼠时，菌株B2F1（Strr）和H414-36 / 89（Strr）的口服50％致死剂量少于10个细菌。喂食O91：H21菌株的垂死小鼠的组织学切片显示广泛的肾小管坏死。但是，血液学结果与溶血性尿毒症综合征的诊断不一致。 SLT在O91：H21 EHEC菌株的毒力中的核心作用得到了以下发现的支持：预先接种针对SLT-II的单克隆抗体的链霉素治疗的小鼠在通过B2F1（Strr）或H414-36 / 89口服攻击后仍然存活（ Strr）。未确定所测试的产生SLT-II的EHEC菌株中毒力变化的基础。但是，观察到EHEC株在小肠粘液中生长的能力与经链霉素处理的小鼠的致死率之间存在相关性。

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