Parsons Brendon D, Zelyas Nathan, Berenger Byron M, Chui Linda
Laboratory Medicine and Pathology, University of Alberta Edmonton, AB, Canada.
Medical Microbiology and Immunology, University of Alberta Edmonton, AB, Canada.
Front Microbiol. 2016 Apr 12;7:478. doi: 10.3389/fmicb.2016.00478. eCollection 2016.
Shiga toxin-producing Escherichia coli (STEC) are responsible for gastrointestinal diseases reported in numerous outbreaks around the world. Given the public health importance of STEC, effective detection, characterization and typing is critical to any medical laboratory system. While non-O157 serotypes account for the majority of STEC infections, frontline microbiology laboratories may only screen for STEC using O157-specific agar-based methods. As a result, non-O157 STEC infections are significantly under-reported. This review discusses recent advances on the detection, characterization and typing of STEC with emphasis on work performed at the Alberta Provincial Laboratory for Public Health (ProvLab). Candidates for the detection of all STEC serotypes include chromogenic agars, enzyme immunoassays (EIA) and quantitative real time polymerase chain reaction (qPCR). Culture methods allow further characterization of isolates, whereas qPCR provides the greatest sensitivity and specificity, followed by EIA. The virulence gene profiles using PCR arrays and stx gene subtypes can subsequently be determined. Different non-O157 serotypes exhibit markedly different virulence gene profiles and a greater prevalence of stx1 than stx2 subtypes compared to O157:H7 isolates. Finally, recent innovations in whole genome sequencing (WGS) have allowed it to emerge as a candidate for the characterization and typing of STEC in diagnostic surveillance isolates. Methods of whole genome analysis such as single nucleotide polymorphisms and k-mer analysis are concordant with epidemiological data and standard typing methods, such as pulsed-field gel electrophoresis and multiple-locus variable number tandem repeat analysis while offering additional strain differentiation. Together these findings highlight improved strategies for STEC detection using currently available systems and the development of novel approaches for future surveillance.
产志贺毒素大肠杆菌（STEC）是世界各地众多疫情中报道的胃肠道疾病的病原体。鉴于STEC对公共卫生的重要性，有效的检测、鉴定和分型对任何医学实验室系统都至关重要。虽然非O157血清型占STEC感染的大多数，但一线微生物实验室可能仅使用基于O157特异性琼脂的方法筛查STEC。因此，非O157 STEC感染的报告严重不足。本综述讨论了STEC检测、鉴定和分型的最新进展，重点介绍了艾伯塔省公共卫生省级实验室（ProvLab）所开展的工作。检测所有STEC血清型的候选方法包括显色琼脂、酶免疫测定（EIA）和定量实时聚合酶链反应（qPCR）。培养方法可进一步鉴定分离株，而qPCR具有最高的灵敏度和特异性，其次是EIA。随后可确定使用PCR阵列的毒力基因谱和stx基因亚型。与O157:H7分离株相比，不同的非O157血清型表现出明显不同的毒力基因谱，且stx1的流行率高于stx2亚型。最后，全基因组测序（WGS）的最新创新使其成为诊断监测分离株中STEC鉴定和分型的候选方法。单核苷酸多态性和k-mer分析等全基因组分析方法与流行病学数据以及脉冲场凝胶电泳和多位点可变数目串联重复分析等标准分型方法一致，同时提供额外的菌株区分。这些研究结果共同强调了使用现有系统改进STEC检测的策略以及未来监测新方法的开发。
