Abstract：
On-site hospital wastewater treatment system widely applying chlorination has been regarded as an important barrier to curb the dissemination of antibiotic resistance. Chlorination-residual viable and viable but non-culturable (VBNC) bacteria probably lead to overestimate the effect of disinfection, while their antibiotic resistance risks imported from hospital effluents to municipal pipe network may be ignored. In this study, we quantified viable/VBNC Escherichia coli and Enterococcus in chlorination of an on-site hospital wastewater treatment system and assessed their antibiotic resistance risks. The numbers of viable/VBNC Escherichia coli and Enterococcus in raw wastewater were detected as high as 5.76-6.34/5.76-6.33 and 5.44-5.76/5.44-5.75 log10(cells/mL). Meanwhile, high proportions of antibiotic-resistant Escherichia coli and Enterococcus to culturable Escherichia coli and Enterococcus were observed, especially carrying ampicillin resistance (22.25-41.70 % and 28.09-54.05 %). Chlorination could remove 0.44-1.88-/0.43-1.88- and 0.29-1.29-/0.28-1.28-log of viable/VBNC and complete culturable Escherichia coli and Enterococcus, but cause antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) to be released outside cells, and possibly further enhance the antibiotic resistance of viable bacteria. Low detections of antibiotics suggested that the occurrence of antibiotic-resistant bacteria (ARB) may not be accompanied by the corresponding antibiotics. Different sampling months had some impacts on above results, while the results were basically stable at different sampling times of hospital daily working period. The high release rates (11.26-13.02 and 11.59-12.98 log10(cells/h)) and cumulative amounts (15.41-16.12 and 15.75-16.14 log10(cells)) of chlorination-residual viable/VBNC Escherichia coli and Enterococcus indirectly assessed the potential risks of bacterial antibiotic resistance entering municipal pipe network. Additionally, the contributions from the corresponding antibiotic ceftazidime, ciprofloxacin, and vancomycin with the cumulative amounts of 2.57-4.85, 5.73-7.50, and 5.21-7.14 kg should also be taken seriously. Residual chlorine could serve as an important signal indicator for the risk assessment.
摘要：
广泛使用氯化法的现场医院污水处理系统已被认为是遏制抗生素耐药性传播的重要障碍。氯化-残留的可行和可行但不可培养的（VBNC）细菌可能会导致高估消毒效果，而从医院废水到市政管网的抗生素耐药性风险可能会被忽视。在这项研究中,我们量化了现场医院废水处理系统氯化过程中的活/VBNC大肠杆菌和肠球菌，并评估了它们的抗生素耐药性风险。原废水中活菌/VBNC大肠杆菌和肠球菌的数量分别高达5.76-6.34/5.76-6.33和5.44-5.76/5.44-5.75log10（细胞/mL）。同时,观察到高比例的抗生素抗性大肠杆菌和肠球菌对可培养的大肠杆菌和肠球菌，尤其是携带氨苄西林耐药（22.25-41.70％和28.09-54.05％）。氯化可以去除0.44-1.88-/0.43-1.88-和0.29-1.29-/0.28-1.28-log活/VBNC和完全可培养的大肠杆菌和肠球菌，但导致抗生素抗性基因（ARGs）和移动遗传元件（MGEs）释放到细胞外，并可能进一步增强活细菌的抗生素抗性。抗生素的低检测表明，抗生素耐药菌（ARB）的发生可能不伴有相应的抗生素。不同的采样月份对上述结果有一定的影响，而在医院日常工作期的不同采样时间，结果基本稳定。氯化残留活/VBNC大肠杆菌和肠球菌的高释放率（11.26-13.02和11.59-12.98log10（细胞/h））和累积量（15.41-16.12和15.75-16.14log10（细胞））间接评估了细菌抗生素耐药性进入市政管网的潜在风险。此外,相应抗生素头孢他啶的贡献，环丙沙星,万古霉素的累积量为2.57-4.85、5.73-7.50和5.21-7.14kg也应认真对待。余氯可作为风险评估的重要信号指标。
