Johnson R P, Holtslander B, Mazzocco A, Roche S, Thomas J L, Pollari F, Pintar K D M
Laboratory for Foodborne Zoonoses, Public Health Agency of Canada, Guelph, Ontario, Canada.
Appl Environ Microbiol. 2014 Apr;80(7):2166-75. doi: 10.1128/AEM.03391-13. Epub 2014 Jan 31.
Verotoxin-producing Escherichia coli (VTEC) strains are the cause of food-borne and waterborne illnesses around the world. Traditionally, surveillance of the human population as well as the environment has focused on the detection of E. coli O157:H7. Recently, increasing recognition of non-O157 VTEC strains as human pathogens and the German O104:H4 food-borne outbreak have illustrated the importance of considering the broader group of VTEC organisms from a public health perspective. This study presents the results of a comparison of three methods for the detection of VTEC in surface water, highlighting the efficacy of a direct VT immunoblotting method without broth enrichment for detection and isolation of O157 and non-O157 VTEC strains. The direct immunoblot method eliminates the need for an enrichment step or the use of immunomagnetic separation. This method was developed after 4 years of detecting low frequencies (1%) of E. coli O157:H7 in surface water in a Canadian watershed, situated within one of the FoodNet Canada integrated surveillance sites. By the direct immunoblot method, VTEC prevalence estimates ranged from 11 to 35% for this watershed, and E. coli O157:H7 prevalence increased to 4% (due to improved method sensitivity). This direct testing method provides an efficient means to enhance our understanding of the prevalence and types of VTEC in the environment. This study employed a rapid evidence assessment (REA) approach to frame the watershed findings with watershed E. coli O157:H7 prevalences reported in the literature since 1990 and the knowledge gap with respect to VTEC detection in surface waters.
产志贺毒素大肠杆菌（VTEC）菌株是全球食源性和水源性疾病的病因。传统上，对人群和环境的监测主要集中在检测大肠杆菌O157:H7。最近，人们越来越认识到非O157 VTEC菌株是人类病原体，以及德国O104:H4食源性疾病暴发，这从公共卫生角度说明了考虑更广泛的VTEC生物体群体的重要性。本研究展示了三种检测地表水中VTEC方法的比较结果，突出了一种无需肉汤增菌的直接VT免疫印迹法在检测和分离O157和非O157 VTEC菌株方面的有效性。直接免疫印迹法无需增菌步骤或使用免疫磁珠分离。该方法是在加拿大一个位于加拿大食品网综合监测点之一的流域对地表水中大肠杆菌O157:H7进行了4年低频率（1%）检测后开发的。通过直接免疫印迹法，该流域VTEC的流行率估计在11%至35%之间，大肠杆菌O157:H7的流行率提高到了4%（由于方法灵敏度提高）。这种直接检测方法为增强我们对环境中VTEC的流行率和类型的了解提供了一种有效手段。本研究采用快速证据评估（REA）方法，将该流域的研究结果与自1990年以来文献中报道的该流域大肠杆菌O157:H7流行率以及地表水中VTEC检测方面的知识差距相结合。
