IRSD, Université de Toulouse, INSERM, INRA, ENVT, UPS, Toulouse, France.
IRSD, Université de Toulouse, INSERM, INRA, ENVT, UPS, Toulouse, France.
Int J Hyg Environ Health. 2018 Mar;221(2):355-363. doi: 10.1016/j.ijheh.2017.12.009. Epub 2017 Dec 29.
Wastewater of human and animal may contain Shiga toxin-producing (STEC) and enteropathogenic (EPEC) Escherichia coli. We evaluated the prevalence of such strains in a wastewater treatment plant (WWTP) receiving both city and slaughterhouse wastewater. PCR screenings were performed on 12,248 E. coli isolates. The prevalence of STEC in city wastewater, slaughterhouse wastewater and treated effluent was 0.22%, 0.07% and 0.22%, respectively. The prevalence of EPEC at the same sampling sites was 0.63%, 0.90% and 0.55%. No significant difference was observed between the sampling points. Treatment had no impact on these prevalences. Enterohemorrhagic E. coli (EHEC) O157:H7 and O111:H8 were isolated from the treated effluent rejected into the river. The characteristics of STEC and EPEC differed according to their origin. City wastewater contained STEC with various stx subtypes associated with serious human disease, whereas slaughterhouse wastewater contained exclusively STEC with stx subtype. All the EPEC strains were classified as atypical and were screened for the ε, γ1 and β1 subtypes, known to be associated with the EHEC mainly involved in human infections in France. In city wastewater, eae subtypes remained largely unidentified; whereas eae-β1 was the most frequent subtype in slaughterhouse wastewater. Moreover, the EPEC isolated from slaughterhouse wastewater were positive for other EHEC-associated virulence markers, including top five serotypes, the ehxA gene, putative adherence genes and OI-122 associated genes. The possibility that city wastewater could contain a pool of stx genes associated with human disease and that slaughterhouse wastewater could contain a pool of EPEC sharing similar virulence genes with EHEC, was highlighted. Mixing of such strains in WWTP could lead to the emergence of EHEC by horizontal gene transfer.
人类和动物的污水可能含有产志贺毒素（STEC）和肠致病性（EPEC）大肠杆菌。我们评估了接收城市和屠宰场污水的污水处理厂（WWTP）中此类菌株的流行情况。对 12248 株大肠杆菌分离株进行了 PCR 筛查。城市污水、屠宰场污水和处理出水的 STEC 流行率分别为 0.22%、0.07%和 0.22%。同一采样点的 EPEC 流行率分别为 0.63%、0.90%和 0.55%。未观察到采样点之间存在显著差异。处理对这些流行率没有影响。从排入河流的处理废水中分离出肠出血性大肠杆菌（EHEC）O157:H7 和 O111:H8。STEC 和 EPEC 的特征因来源而异。城市污水中含有各种与严重人类疾病相关的 stx 亚型的 STEC，而屠宰场污水中仅含有 stx 亚型的 STEC。所有 EPEC 菌株均被归类为非典型菌株，并针对与法国主要与人类感染相关的 EHEC 相关的 ε、γ1 和 β1 亚型进行了筛查。在城市污水中，eae 亚型仍未得到广泛鉴定；而 eae-β1 是屠宰场污水中最常见的亚型。此外，从屠宰场污水中分离出的 EPEC 还携带其他与 EHEC 相关的毒力标记物，包括五个主要血清型、ehxA 基因、推定的粘附基因和与 OI-122 相关的基因。研究结果强调了城市污水可能含有与人类疾病相关的 stx 基因库，而屠宰场污水可能含有与 EHEC 具有相似毒力基因的 EPEC 基因库。这些菌株在 WWTP 中的混合可能导致 EHEC 通过水平基因转移的出现。
