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首页> 外文期刊>Applied and Environmental Microbiology >Identification of Genetic Markers for Differentiation of Shiga Toxin-Producing, Enteropathogenic, and Avirulent Strains of Escherichia coli O26
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Identification of Genetic Markers for Differentiation of Shiga Toxin-Producing, Enteropathogenic, and Avirulent Strains of Escherichia coli O26

机译：鉴定产志贺菌O26产志贺毒素，肠致病和无毒菌株的遗传标记

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Shiga toxin-producing Escherichia coli (STEC) O26 is one of the top five enterohemorrhagic E. coli (EHEC) O groups most often associated with hemorrhagic colitis and hemolytic uremic syndrome (HUS) worldwide. STEC O26 is considered to have evolved from enteropathogenic (EPEC) O26 strains through the acquisition of Shiga toxin (Stx)-encoding genes. Our PCR data identified several STEC-like strains expressing all features of STEC except Stx production and carrying remnants of Stx phages that were probably derivatives of EHEC O26. EHEC and EPEC O26 strains phenotypically resemble O26 EHEC-like and apathogenic E. coli O26 strains and are therefore undistinguishable by cultural methods. A clear discrimination between the different O26 groups is required for diagnostics in patients and for control of food safety. To develop an assay for specific detection of EHEC and EHEC-like O26 strains, we used a high-throughput PCR approach for selection of discriminative genetic markers among 33 tested genes mostly encoding type III secretion system effector proteins. The genes ECs1822, nleH1-2, nleA, nleC, nleH1-1, nleG, nleG2, nleG6-1, nleG6-2, espJ, espM2, nleG8-2, espG, ent (or espL2), nleB, nleE, efa1, and espB were detected at different frequencies in O26 EHEC, EHEC-like, and EPEC strains, indicating the possible role of these genes in virulence of human pathogenic O26 strains. The espK and espN genes were detected only in EHEC and EHEC-like O26 strains. espK was present in 99.14% of EHEC and 91.14% of EHEC-like O26 strains and was hence the best candidate as a genetic marker for characterizing these pathogroups. These data were corroborated by a genotyping real-time PCR test based on allelic discrimination of the arcA (aerobic respiratory control protein A) gene. The results indicate that a combination of molecular detection tools for O26 wzx (wzxO26), eae-beta, stx, espK, and arcA genotyping is highly discriminative for clear identification of EHEC and EHEC-like E. coli O26 strains. This simple diagnostic test might be applicable in hospital service laboratories or public health laboratories to test strains isolated from stools of patients suffering from diarrhea.
机译：产生志贺毒素的大肠埃希菌（OSC）O26是世界上最常与出血性结肠炎和溶血性尿毒症综合征（HUS）相关的五个大肠出血性大肠杆菌（EHEC）O组之一。 STEC O26被认为是通过获取志贺毒素（Stx）编码基因从肠致病性（EPEC）O26菌株进化而来的。我们的PCR数据鉴定出了几种表达STEC的所有特征的类STEC菌株，除了Stx产生和携带可能是EHEC O26衍生物的Stx噬菌体的残余物。 EHEC和EPEC O26菌株在表型上类似于O26 EHEC样和致病性大肠杆菌O26菌株，因此无法通过培养方法加以区分。为了对患者进行诊断并控制食品安全，需要对O26不同组之间进行明确区分。为了开发一种特异性检测EHEC和类似EHEC的O26菌株的测定方法，我们使用了一种高通量PCR方法，在33个主要编码III型分泌系统效应蛋白的被测基因中选择了有区别的遗传标记。基因ECs1822，nleH1-2，nleA，nleC，nleH1-1，nleG，nleG2，nleG6-1，nleG6-2，espJ，espM2，nleG8-2，espG，ent（或espL2），nleB，nleE，efa1，在O26 EHEC，EHEC-like和EPEC菌株中以不同的频率检测到了EspB和espB，表明这些基因可能在人致病性O26菌株的毒力中发挥作用。 espK和espN基因仅在EHEC和类似EHEC的O26菌株中检测到。 espK存在于99.14％的EHEC和91.14％的EHEC样O26菌株中，因此是表征这些病原体的最佳遗传标记。这些数据通过基于arcA（有氧呼吸控制蛋白A）基因的等位基因识别的基因分型实时PCR测试得到证实。结果表明，针对O26 wzx（wzxO26），eae-beta，stx，espK和arcA基因分型的分子检测工具的组合对于高度识别EHEC和类似EHEC的O26大肠杆菌O26菌株具有很高的判别力。这种简单的诊断测试可能适用于医院服务实验室或公共卫生实验室，以测试从腹泻患者粪便中分离出的菌株。

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