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首页> 外文期刊>Applied Microbiology >Pathogenic Potential, Genetic Diversity, and Population Structure of Escherichia coli Strains Isolated from a Forest-Dominated Watershed (Comox Lake) in British Columbia, Canada
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Pathogenic Potential, Genetic Diversity, and Population Structure of Escherichia coli Strains Isolated from a Forest-Dominated Watershed (Comox Lake) in British Columbia, Canada

机译：从加拿大不列颠哥伦比亚省一个以森林为主的流域（Comox湖）分离的大肠杆菌菌株的致病潜力，遗传多样性和种群结构

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Escherichia coli isolates ( n = 658) obtained from drinking water intakes of Comox Lake (2011 to 2013) were screened for the following virulence genes (VGs): stx _(1) and stx _(2) (Shiga toxin-producing E. coli [STEC]), eae and the adherence factor (EAF) gene (enteropathogenic E. coli [EPEC]), heat-stable (ST) enterotoxin (variants STh and STp) and heat-labile enterotoxin (LT) genes (enterotoxigenic E. coli [ETEC]), and ipaH (enteroinvasive E. coli [EIEC]). The only genes detected were eae and stx _(2), which were carried by 37.69% ( n = 248) of the isolates. Only eae was harbored by 26.74% ( n = 176) of the isolates, representing potential atypical EPEC strains, while only stx _(2) was detected in 10.33% ( n = 68) of the isolates, indicating potential STEC strains. Moreover, four isolates were positive for both the stx _(2) and eae genes, representing potential EHEC strains. The prevalence of VGs ( eae or stx _(2)) was significantly ( P < 0.0001) higher in the fall season, and multiple genes ( eae plus stx _(2)) were detected only in fall. Repetitive element palindromic PCR (rep-PCR) fingerprint analysis of 658 E. coli isolates identified 335 unique fingerprints, with an overall Shannon diversity ( H ′) index of 3.653. Diversity varied among seasons over the years, with relatively higher diversity during fall. Multivariate analysis of variance (MANOVA) revealed that the majority of the fingerprints showed a tendency to cluster according to year, season, and month. Taken together, the results indicated that the diversity and population structure of E. coli fluctuate on a temporal scale, reflecting the presence of diverse host sources and their behavior over time in the watershed. Furthermore, the occurrence of potentially pathogenic E. coli strains in the drinking water intakes highlights the risk to human health associated with direct and indirect consumption of untreated surface water.
机译：从Comox湖（2011年至2013年）的饮水中获取的大肠杆菌分离物（n = 658）筛选出以下毒力基因（VG）：stx _（1）和stx _（2）（产生志贺毒素的E.大肠杆菌（STEC]），eae和粘附因子（EAF）基因（致病性大肠杆菌[EPEC]），热稳定（ST）肠毒素（变体STh和STp）和不耐热肠毒素（LT）基因（肠毒素E大肠杆菌[ETEC]）和ipaH（侵害性大肠杆菌[EIEC]）。检测到的唯一基因是eae和stx _（2），它们由37.69％（n = 248）的分离株携带。分离株中只有eae占26.74％（n = 176），代表潜在的非典型EPEC菌株，而分离株中只有10.13％（n = 68）中检测到stx_（2），表明可能是STEC菌株。此外，stx _（2）和eae基因的四个分离株均为阳性，代表潜在的EHEC菌株。 VGs（eae或stx _（2））的患病率在秋季显着升高（P <0.0001），并且仅在秋天检测到多个基因（eae加stx _（2））。 658株大肠杆菌的重复元素回文PCR（rep-PCR）指纹分析确定了335个独特的指纹，总体香农多样性（H'）指数为3.653。这些年来，不同季节之间的多样性各不相同，秋季则相对较高。多变量方差分析（MANOVA）显示，大多数指纹根据年，季节和月份显示出聚集的趋势。两者合计，结果表明大肠杆菌的多样性和种群结构在时间尺度上波动，反映出分水岭中各种宿主源的存在及其随时间的行为。此外，饮用水摄入中潜在致病性大肠杆菌菌株的出现突出了与未经处理的地表水的直接和间接消耗相关的对人类健康的风险。

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