title: Inactivation and reactivation of antibiotic-resistant bacteria by chlorination in secondary effluents of a municipal wastewater treatment plant.
abstract: Reports state that chlorination of drinking water and wastewater affects the proportions of antibiotic-resistant bacteria by potentially assisting in microbial selection. Studies on the effect of chlorination on like species of antibiotic-resistant bacteria, however, have shown to be conflicting; furthermore, few studies have inspected the regrowth or reactivation of antibiotic-resistant bacteria after chlorination in wastewater. To understand the risks of chlorination resulting from potentially selecting for antibiotic-resistant bacteria, inactivation and reactivation rates of both total heterotrophic bacteria and antibiotic-resistant bacteria (including penicillin-, ampicillin-, tetracycline-, chloramphenicol-, and rifampicin-resistant bacteria) were examined after chlorinating secondary effluent samples from a municipal wastewater treatment plant in this study. Our experimental results indicated similar inactivation rates of both total heterotrophic bacteria and antibiotic-resistant bacteria. Microbial community composition, however, was affected by chlorination: treating samples with 10 mg Cl(2)/L for 10 min resulted in chloramphenicol-resistant bacteria accounting for nearly 100% of the microbial population in contrast to 78% before chlorination. This trend shows that chlorination contributes to selection of some antibiotic-resistant strains. Reactivation of antibiotic-resistant bacteria occurred at 2.0 mg Cl(2)/L for 10 min; specifically, chloramphenicol-, ampicillin-, and penicillin-resistant bacteria were the three prevalent groups present, and the reactivation of chloramphenicol-resistant bacteria exceeded 50%. Regrowth and reactivation of antibiotic-resistant bacteria in secondary effluents after chlorination with a long retention time could threaten public health security during wastewater reuse.
authors: State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, PR China.
authors: Jing-Jing
authors: JJ
authors: Huang
authors: Hong-Ying
authors: HY
authors: Hu
authors: Fang
authors: F
authors: Tang
authors: Yi
authors: Y
authors: Li
authors: Sun-Qin
authors: SQ
authors: Lu
authors: Yun
authors: Y
authors: Lu
mesh_terms: D001419:Bacteria / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D002713:Chlorine / Q000633:toxicity*; D002947:Cities; D004202:Disinfectants / Q000633:toxicity*; D024881:Drug Resistance, Bacterial / Q000187:drug effects*; D054879:Halogenation; D050296:Microbial Viability / Q000187:drug effects; D012722:Sewage / Q000382:microbiology; D014865:Waste Disposal, Fluid / Q000379:methods*; D018508:Water Purification / Q000379:methods
chemical_list: D004202:Disinfectants; D012722:Sewage; D002713:Chlorine