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肠出血性大肠杆菌O91:H21临床分离株在经口感染小鼠模型中的毒力

Virulence of enterohemorrhagic Escherichia coli O91:H21 clinical isolates in an orally infected mouse model.

作者信息

Lindgren S W, Melton A R, O'Brien A D

机构信息

Department of Microbiology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799.

出版信息

Infect Immun. 1993 Sep;61(9):3832-42. doi: 10.1128/iai.61.9.3832-3842.1993.

Abstract

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.

摘要

先前已证明,产生高水平II型志贺样毒素(SLT-II)但不产生SLT-I的大肠杆菌K-12菌株,在经链霉素处理的口服感染小鼠模型中具有毒性。在本研究中,我们测试了从出血性结肠炎或溶血尿毒综合征患者中分离出的几种产SLT-II的肠出血性大肠杆菌(EHEC)菌株的毒性。所有测试菌株都能够在小鼠肠道中定殖。然而,只有两株菌株对小鼠始终具有毒性:O91:H21菌株B2F1(Strr),先前已证明其携带两份与slt-II相关的毒素拷贝;以及O91:H21菌株H414-36/89(Strr),本研究发现该菌株含有来自slt-II组的三个基因。给经链霉素处理的小鼠喂食菌株B2F1(Strr)和H414-36/89(Strr)时,其口服50%致死剂量小于10个细菌。给喂食O91:H21菌株的濒死小鼠制作的组织学切片显示广泛的肾小管坏死;然而,血液学结果与溶血尿毒综合征的诊断不一致。用针对SLT-II的单克隆抗体预先接种的经链霉素处理的小鼠,在口服感染B2F1(Strr)或H414-36/89(Strr)后存活,这一发现支持了SLT在O91:H21 EHEC菌株毒性中的核心作用。所测试的产SLT-II的EHEC菌株之间毒性差异的基础尚未确定。然而,观察到EHEC菌株在小肠黏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。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/cdb9/281084/fc8f87b5097e/iai00021-0271-a.jpg

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