Even though sediment Escherichia coli is a common source of contamination in freshwater environments, their characteristics such as virulence genes, biofilm forming capacity, antibiotic resistance, and level of reactive oxygen species (ROS) are not well understood. This study examined E. coli from freshwater sediments, sewage, and a collection of O157 isolates. Multiplex PCR analysis revealed that none of the sediment and 3% of the sewage isolates contained diarrheagenic E. coli genes. However, 12.5% of sediment and 42.4% of sewage isolates contained one or more uropathogenic genes. Biofilm assays determined that sediment E. coli were significantly better biofilm formers (p < 0.001), forming 2- and 3.5-times as much biofilm as sewage and O157 E. coli, respectively. The antibiotic-resistance patterns illustrated that the E. coli belonged to three distinct groups with sediment being most susceptible and sewage being most resistant (p < 0.05). Although the planktonic cellular ROS levels of the three sample groups tested were not different from each other, the level of ROS in biofilm cells was eightfold lower than their planktonic counterparts (p < 0.001). Cells with higher ROS tolerance have been shown to have more tolerance to bactericidal antibiotics; however, the antibiotic-resistance levels of the bacteria in this study did not correlate to their cellular ROS concentrations.

尽管沉积物大肠杆菌是淡水环境中常见的污染源，但它们的毒力基因、生物膜形成能力、抗生素抗性和活性氧 (ROS) 水平等特征尚不清楚。本研究检测了淡水沉积物、污水和 O157 分离株中的大肠杆菌。多重 PCR 分析表明，没有沉积物和 3% 的污水分离株含有致腹泻的大肠杆菌基因。然而，12.5% 的沉积物和 42.4% 的污水分离株含有一种或多种尿路致病基因。生物膜测定确定沉积物大肠杆菌是明显更好的生物膜形成剂（p < 0.001)，形成的生物膜分别是污水和 O157大肠杆菌的 2 倍和 3.5 倍。抗生素抗性模式表明大肠杆菌属于三个不同的群体，其中沉积物最敏感，污水最抗药性 ( p  < 0.05)。尽管测试的三个样品组的浮游细胞 ROS 水平彼此没有差异，但生物膜细胞中的 ROS 水平比它们的浮游对应物低八倍（p  < 0.001）。已证明具有较高 ROS 耐受性的细胞对杀菌抗生素具有更高的耐受性；然而，本研究中细菌的抗生素抗性水平与其细胞 ROS 浓度无关。