Institute of Environmental Science and Research, Ltd., Christchurch Science Centre, Christchurch, New Zealand.
Foodborne Pathog Dis. 2012 Dec;9(12):1064-70. doi: 10.1089/fpd.2012.1226.
A robust semiquantitative method for measuring the colonization potential of O157 enterohemorrhagic Escherichia coli (EHEC) strains was developed combining an established ex vivo model infection system, bovine in vitro organ culture, with detection of bacteria attached to tissue sections by immunofluorescent assay (bIVOC-IFA) using Quantum dot(®) nanocrystal technology. The method was tested on ten O157 strains chosen to reflect a diversity of genotypes found in New Zealand based on the novel polymerase chain reaction-binary typing (P-BIT) system. High- and low-colonizing EHEC O157 strains were identified using bIVOC-IFA, with the highest colonizing strain belonging to the pulsed-field gel electrophoresis type most commonly identified from New Zealand beef meat. Furthermore, all of the toxigenic O157 strains exhibiting a low-colonizing phenotype were closely related, belonging to the same P-BIT genotype cluster. Future use of this method to characterize EHEC strains could provide valuable information for risk assessment and risk management interventions aimed at improving food safety along the beef farm to fork continuum.
建立了一种稳健的半定量方法，用于测量 O157 肠出血性大肠杆菌 (EHEC) 菌株的定植潜力，该方法结合了已建立的体外模型感染系统，即牛体外器官培养，以及使用量子点（®）纳米晶体技术通过免疫荧光检测（bIVOC-IFA）检测附着在组织切片上的细菌。该方法在基于新型聚合酶链反应-二进制分型（P-BIT）系统的新西兰发现的多种基因型的 10 株 O157 菌株上进行了测试。使用 bIVOC-IFA 鉴定了高定植和低定植 EHEC O157 菌株，最高定植菌株属于新西兰牛肉中最常发现的脉冲场凝胶电泳类型。此外，所有表现出低定植表型的产毒 O157 菌株密切相关，属于同一 P-BIT 基因型簇。未来使用该方法对 EHEC 菌株进行表征，可以为旨在沿着牛肉从农场到餐桌的连续体提高食品安全的风险评估和风险管理干预措施提供有价值的信息。
