Kanankege Kaushi S T, Anklam Kelly S, Fick Catherine M, Kulow Megan J, Kaspar Charles W, Ingham Barbara H, Milkowski Andrew, Döpfer Dörte
Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI, USA.
Department of Bacteriology, College of Agricultural and Life Sciences, University of Wisconsin, Madison, WI, USA.
Food Microbiol. 2017 May;63:228-238. doi: 10.1016/j.fm.2016.11.023. Epub 2016 Dec 2.
Six major Shiga toxin producing Escherichia coli (STEC) serogroups: O26, O103, O145, O111, O121, and O45 have been declared as adulterants in federally inspected raw beef in the USA effective June 4th, 2012 in addition to the routinely tested STEC O157: H7. This study tests a real-time multiplex PCR assay and pooling of the samples to optimize the detection and quantification (prevalence and contamination) of six major non-O157 STEC, regardless of possessing Shiga toxins. To demonstrate the practicality, one large-scale slaughter plant (Plant LS) and one small-scale slaughter plant (Plant SS) located in the Mid-Western USA were sampled, in 2011, before the establishment of 2013 USDA laboratory protocols. Carcasses were sampled at consecutive intervention stations and beef trimmings were collected at the end of the fabrication process. Plant SS had marginally more contaminated samples than Plant LS (p-value 0.08). The post-hide removal wash, steam pasteurization, and lactic acid (≤5%) spray used in Plant LS seemed to reduce the six serogroups effectively, compared to the hot-water wash and 7-day chilling at Plant SS. Compared to the culture isolation methods, quantification of the non-O157 STEC using real-time PCR may be an efficient way to monitor the efficacy of slaughter line interventions.
除了常规检测的产志贺毒素大肠杆菌O157:H7外，美国自2012年6月4日起宣布，六种主要的产志贺毒素大肠杆菌（STEC）血清型：O26、O103、O145、O111、O121和O45为联邦检查的生牛肉中的掺假物。本研究测试了一种实时多重聚合酶链反应（PCR）检测方法以及样本合并，以优化六种主要非O157 STEC的检测和定量（流行率和污染情况），无论其是否产志贺毒素。为了证明该方法的实用性，2011年，在美国农业部2013年实验室规程制定之前，对位于美国中西部的一家大型屠宰厂（工厂LS）和一家小型屠宰厂（工厂SS）进行了采样。在连续的干预站对胴体进行采样，并在加工过程结束时收集牛肉边角料。工厂SS的受污染样本略多于工厂LS（p值为0.08）。与工厂SS使用的热水清洗和7天冷藏相比，工厂LS使用的去毛后清洗、蒸汽巴氏杀菌和乳酸（≤5%）喷雾似乎能有效减少这六种血清型。与培养分离方法相比，使用实时PCR对非O157 STEC进行定量可能是监测屠宰线干预效果的有效方法。
