DVGW-Technologiezentrum Wasser (TZW), Karlsruher Staße 84, D-76139, Karlsruhe, Germany.
CSIRO Oceans and Atmosphere, Ecosciences Precinct, 41 Boggo Road, Brisbane, Qld, 4102, Australia.
Int J Hyg Environ Health. 2019 Apr;222(3):541-548. doi: 10.1016/j.ijheh.2019.02.002. Epub 2019 Feb 7.
Efficient treatment methods for the removal of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) from drinking water are needed to reduce health risks. However, there is a lack of empirical data on ARB and ARG removal during conventional water disinfection processes. In this study, the removal of ARB and ARGs by three disinfection processes (chlorination, ozonation, and UV treatment) was investigated on a laboratory scale using Escherichia coli and Enterococcus faecium carrying ARGs. Bacterial inactivation was determined by plate count methods, and ARG damage was quantified using real-time PCR. Only for ozone treatment, similar inactivation rates for bacterial cells and ARGs were observed when 1 mgL of ozone, with a contact time of 5 min, was used, which resulted in a 5.0 log reduction of bacterial cells and a 4.3-4.6 log reduction of ARGs. For chlorine and UV, inactivation of bacterial cells was observed at lower doses than those needed for the decrease of ARG copy numbers. The use of 0.5 mgL free chlorine (30 min contact time) led to a 3.8-5.6 log reduction of the bacterial numbers and to a 0.8-2.8 log reduction of ARGs. Ultraviolet light irradiation with 600 J*m resulted in a 4.8-5.5 log reduction of bacterial cells, but in a negligible reduction (0-1.0 log) of ARGs. Although UV and chlorine treatments were effective in the inactivation of bacterial cells, incomplete degradation of ARGs was observed. Therefore, plasmid-borne ARGs can potentially be transferred to other bacteria even after the disinfection process. Our results provide important insights into the fate of ARGs during drinking water disinfection processes.
需要有效的方法来去除饮用水中的抗生素耐药菌（ARB）和抗生素耐药基因（ARGs），以降低健康风险。然而，在常规水消毒过程中，关于 ARB 和 ARG 去除的经验数据还很缺乏。在这项研究中，使用携带 ARGs 的大肠杆菌和粪肠球菌，在实验室规模上研究了三种消毒工艺（氯化、臭氧和 UV 处理）对 ARB 和 ARGs 的去除效果。通过平板计数法确定细菌失活动力学，并用实时 PCR 定量 ARG 损伤。只有在臭氧处理中，当使用 1 mgL 的臭氧且接触时间为 5 min 时，细菌细胞和 ARGs 具有相似的失活动力学，导致细菌细胞减少 5.0 log，ARGs 减少 4.3-4.6 log。对于氯和 UV，在降低 ARG 拷贝数所需的剂量下观察到细菌细胞的失活。使用 0.5 mgL 的游离氯（30 min 接触时间）可使细菌数量减少 3.8-5.6 log，并使 ARGs 减少 0.8-2.8 log。600 J*m 的紫外线照射可使细菌细胞减少 4.8-5.5 log，但 ARGs 的减少可忽略不计（0-1.0 log）。尽管 UV 和氯处理对细菌细胞的失活有效，但观察到 ARGs 不完全降解。因此，即使在消毒过程之后，质粒携带的 ARGs 也可能转移到其他细菌中。我们的研究结果为饮用水消毒过程中 ARGs 的命运提供了重要的见解。
