The presence of antibiotic resistance in wastewater sparked a great interest in investigating the inactivation of antibiotic-resistant bacteria by disinfecting agents. In this study, the inactivation kinetics of multidrug-resistant E. coli and enterococci by an emerging environmentally-friendly disinfectant, peracetic acid (PAA), in wastewater and phosphate buffer at pH 6.5 and pH 7.5, were characterized. It was demonstrated that the inactivation of the studied multidrug-resistant bacteria was governed by their exposure to PAA, i.e., integral of the PAA concentration over time (integral CT or ICT). Both regimes of the PAA inactivation of bacteria, i.e., initial resistance followed by a faster inactivation, were described well by an ICT-based Chick-Watson inactivation kinetic model. In wastewater at pH 7.5, the model-predicted ICT requirements showed that the multidrug-resistant enterococci were less susceptible to PAA than E. coli, e.g., to achieve a 3-log reduction, an ICT of 32.7 mg min/L and 23.4 mg min/L was needed, respectively. No regrowth of the studied bacteria was observed after 72 h from PAA disinfection at 25 ± 1 °C. Soluble constituents of wastewater decreased the PAA inactivation of both multidrug-resistant bacteria, i.e., higher inactivation was observed in phosphate buffer than wastewater at the same pH of 7.5. In phosphate buffer, a lower pH of 6.5 resulted in higher inactivation of multidrug-resistant E. coli compared with pH 7.5, but it did not affect the PAA inactivation of multidrug-resistant enterococci. A comparison with the most commonly used chemical disinfectant, chlorine, showed higher inactivation of both multidrug-resistant bacteria by chlorine and higher chlorine decay than PAA. The results of the present study may have implications in designing a PAA disinfection process, aiming at controlling antibiotic resistance, in terms of selecting a suitable fecal indicator and optimizing disinfectant dosing.

废水中抗生素抗性的存在引发了人们对通过消毒剂灭活抗生素抗性细菌的研究的极大兴趣。在本研究中，多重耐药大肠杆菌的灭活动力学在 pH 6.5 和 pH 7.5 的废水和磷酸盐缓冲液中，对一种新兴的环保消毒剂过乙酸 (PAA) 和肠球菌进行了表征。结果表明，所研究的多重耐药菌的灭活受它们暴露于 PAA 的影响，即 PAA 浓度随时间的积分（积分 CT 或 ICT）。基于 ICT 的 Chick-Watson 灭活动力学模型很好地描述了 PAA 灭活细菌的两种机制，即最初的抗性，然后是更快的灭活。在 pH 值为 7.5 的废水中，模型预测的 ICT 要求表明耐多药肠球菌对 PAA 的敏感性低于大肠杆菌例如，要实现 3-log 降低，分别需要 32.7 mg min/L 和 23.4 mg min/L 的 ICT。在 25 ± 1 °C 的 PAA 消毒 72 小时后，未观察到所研究细菌的再生。废水的可溶性成分降低了两种多药耐药细菌的 PAA 失活，即在磷酸盐缓冲液中观察到的失活率高于相同 pH 值为 7.5 的废水。在磷酸盐缓冲液中，6.5 的较低 pH 值导致多重耐药大肠杆菌的更高灭活与 pH 7.5 相比，但不影响多药耐药肠球菌的 PAA 灭活。与最常用的化学消毒剂氯相比，氯对耐多药细菌的灭活率更高，氯衰减率高于 PAA。本研究的结果可能对设计 PAA 消毒过程有影响，旨在控制抗生素耐药性，在选择合适的粪便指示剂和优化消毒剂剂量方面。