Nadya Stephanie, Delaquis Pascal, Chen Jessica, Allen Kevin, Johnson Roger P, Ziebell Kim, Laing Chad, Gannon Victor, Bach Susan, Topp Edward
Food, Nutrition and Health, Faculty of Land and Food Systems, University of British Columbia Vancouver, BC, Canada.
Agriculture and Agri-Food Canada, Summerland Research and Development Centre Summerland, BC, Canada.
Front Cell Infect Microbiol. 2016 Apr 5;6:36. doi: 10.3389/fcimb.2016.00036. eCollection 2016.
A hydrophobic grid membrane filtration-Shiga toxin immunoblot method was used to examine the prevalence of Shiga toxin-producing Escherichia coli (STEC) in four watersheds located in the Lower Mainland of British Columbia, Canada, a region characterized by rapid urbanization and intensive agricultural activity. STEC were recovered from 21.6, 23.2, 19.5, and 9.2% of surface water samples collected monthly from five sites in each watershed over a period of 1 year. Overall prevalence was subject to seasonal variation however, ranging between 13.3% during fall months and 34.3% during winter months. STEC were also recovered from 23.8% of sediment samples collected in one randomly selected site. One hundred distinct STEC isolates distributed among 29 definitive and 4 ambiguous or indeterminate serotypes were recovered from water and sediments, including isolates from Canadian "priority" serogroups O157 (3), O26 (4), O103 (5), and O111 (7). Forty seven isolates were further characterized by analysis of whole genome sequences to detect Shiga toxin gene (stx 1 and stx 2), intimin gene (eaeA) allelic variants and acquired virulence factors. These analyses collectively showed that surface waters from the region support highly diverse STEC populations that include strains with virulence factors commonly associated with human pathotypes. The present work served to characterize the microbiological hazard implied by STEC to support future assessments of risks to public health arising from non-agricultural and agricultural uses of surface water resources in the region.
采用疏水网格膜过滤-志贺毒素免疫印迹法，对加拿大不列颠哥伦比亚省低陆平原四个流域产志贺毒素大肠杆菌（STEC）的流行情况进行了检测。该地区城市化进程迅速，农业活动密集。在一年的时间里，每月从每个流域的五个地点采集地表水样本，STEC的检出率分别为21.6%、23.2%、19.5%和9.2%。总体流行率存在季节性变化，秋季为13.3%，冬季为34.3%。在一个随机选择的地点采集的沉积物样本中，STEC的检出率也为23.8%。从水和沉积物中分离出100株不同的STEC菌株，分布在29种确定型和4种模糊或不确定血清型中，包括来自加拿大“优先”血清群O157（3株）、O26（4株）、O103（5株）和O111（7株）的菌株。通过分析全基因组序列，对47株菌株进行了进一步鉴定，以检测志贺毒素基因（stx 1和stx 2）、紧密素基因（eaeA）等位基因变体和获得性毒力因子。这些分析共同表明，该地区的地表水支持高度多样化的STEC菌群，其中包括具有通常与人类致病型相关的毒力因子的菌株。本研究旨在描述STEC所隐含的微生物危害，以支持未来对该地区地表水资源非农业和农业用途对公众健康产生的风险进行评估。
