Fate of Antibiotic Resistant Bacteria and Genes during Wastewater Chlorination: Implication for Antibiotic Resistance Control

This study investigated fates of nine antibiotic-resistant bacteria as well as two series of antibiotic resistance genes in wastewater treated by various doses of chlorine (0, 15, 30, 60, 150 and 300 mg Cl2 min/L). The results indicated that chlorination was effective in inactivating antibiotic-resistant bacteria. Most bacteria were inactivated completely at the lowest dose (15 mg Cl2 min/L). By comparison, sulfadiazine- and erythromycin-resistant bacteria exhibited tolerance to low chlorine dose (up to 60 mg Cl2 min/L). However, quantitative real-time PCRs revealed that chlorination decreased limited erythromycin or tetracycline resistance genes, with the removal levels of overall erythromycin and tetracycline resistance genes at 0.42 ± 0.12 log and 0.10 ± 0.02 log, respectively. About 40% of erythromycin-resistance genes and 80% of tetracycline resistance genes could not be removed by chlorination. Chlorination was considered not effective in controlling antimicrobial resistance. More concern needs to be paid to the potential risk of antibiotic resistance genes in the wastewater after chlorination.

本研究针对经不同剂量氯（0、15、30、60、150及300 mg Cl₂ min/L）处理的废水，探究了9种耐药细菌（antibiotic-resistant bacteria）以及两类耐药基因（antibiotic resistance genes）的归趋。研究结果表明，氯化处理对灭活耐药细菌效果显著，在最低剂量（15 mg Cl₂ min/L）条件下，大部分细菌可被完全灭活；相较而言，抗磺胺嘧啶（sulfadiazine）与抗红霉素（erythromycin）细菌对低剂量氯（最高可达60 mg Cl₂ min/L）表现出耐受性。然而定量实时聚合酶链式反应（Quantitative Real-time PCR，qPCR）结果显示，氯化处理对红霉素或四环素（tetracycline）耐药基因的去除效果有限：总体红霉素耐药基因的对数去除量为0.42±0.12 log，四环素耐药基因则为0.10±0.02 log，约40%的红霉素耐药基因与80%的四环素耐药基因无法通过氯化处理被去除。综上，氯化处理对控制抗菌耐药性（antimicrobial resistance）的效果不佳，需更加关注氯化处理后废水中耐药基因所潜藏的潜在风险。