CSIRO Land and Water Flagship, Ecosciences Precinct, 41 Boggo Road, Dutton Park, Brisbane, QLD, 4102, Australia.
School of Public Health, University of Queensland, Brisbane, QLD, Australia.
Environ Sci Pollut Res Int. 2017 Aug;24(22):18263-18272. doi: 10.1007/s11356-017-9497-0. Epub 2017 Jun 21.
Aquatic environments are now recognized secondary habitat of potentially pathogenic Escherichia coli. In this study, PCR-based analyses were used to determine the phylogenetic composition and frequency of occurrence of eight clinically significant virulence genes (VGs) in E. coli isolates from sub-tropical Brisbane and cool temperate Tasmania freshwater in Australia. In Brisbane, non-commensal E. coli isolates belonging to the B2 and D phylogenetic group were dominant (72%). A significantly higher number (P < 0.05) of E. coli carrying VGs were detected in the sub-tropical freshwaters compared to the cool temperate water. Furthermore, diarrheagenic pathotype (EHEC) was also observed in the sub-tropical freshwater. The genes east1 and eaeA were significantly more common (P < 0.00001) than other VGs. The eaeA gene which codes for intimin protein along with toxin genes east1, stx , stx , and LT1 were mostly detected in phylogenetic groups B2 and D. The ANOVA results also suggested a statistically significant difference (P < 0.016) between the VGs carried by phylogenetic groups B2 and D. Class 1 integrase (intl1) and class 2 integrase (intl2) genes were detected in 38 (24.83%) and 23 (15.03%) of E. coli isolates, respectively. The Gretna site (Tasmania) with known fecal input from bovine and ovine sources had the highest number of E. coli carrying intl1 (29%) and intl2 (13%) genes. In addition, class 2 integron was more commonly detected in the phylogenetic group B2. The results of this study highlight the need to better understand sources and reasons for the high prevalence of E. coli carrying clinically significant VGs in a sub-tropical environment and its public health implications.
水生环境现在被认为是潜在致病性大肠杆菌的次要栖息地。在这项研究中，我们使用基于 PCR 的分析方法来确定来自澳大利亚亚热带布里斯班和凉爽温带塔斯马尼亚淡水的大肠杆菌分离株中 8 种临床重要毒力基因（VGs）的系统发育组成和发生频率。在布里斯班，属于 B2 和 D 系统发育群的非共生大肠杆菌分离株占主导地位（72%）。与凉爽温带水相比，亚热带淡水检测到携带 VGs 的大肠杆菌数量显著增加（P<0.05）。此外，亚热带淡水中还观察到肠出血性大肠杆菌（EHEC）。基因 east1 和 eaeA 比其他 VGs 更为常见（P<0.00001）。编码紧密素蛋白的 eaeA 基因以及毒素基因 east1、stx 、stx 和 LT1 主要在 B2 和 D 系统发育群中检测到。方差分析结果还表明，B2 和 D 系统发育群携带的 VGs 之间存在统计学上的显著差异（P<0.016）。类 1 整合酶（intl1）和类 2 整合酶（intl2）基因分别在 38 株（24.83%）和 23 株（15.03%）大肠杆菌分离株中检测到。有已知牛和羊粪输入的 Gretna 地点（塔斯马尼亚）携带 intl1（29%）和 intl2（13%）基因的大肠杆菌数量最多。此外，类 2 整合子在 B2 系统发育群中更为常见。这项研究的结果强调了需要更好地了解在亚热带环境中携带临床重要 VGs 的大肠杆菌高流行率的来源和原因及其对公共卫生的影响。
