南京地区污水厂、自来水厂及长江水域MCR-1和NDM-1携带菌耐药特征
The Antibiotic Resistance Profiles of MCR-1 and NDM-1 Hosting Bacteria in a Wastewater Treatment Plant, Drinking Water Treatment Plant and the Yangtze River in Nanjing
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摘要: 为了研究以多粘菌素耐药基因(MCR-1)和新德里金属β-内酰胺酶-1基因(NDM-1)携带菌为代表的“超级细菌”在地表水中的环境行为，以长江南京段典型水域及邻近城市污水厂和自来水厂为研究对象，考察了MCR-1和NDM-1携带菌的耐药特性及其变化特征。结果发现，污水厂进水和生物处理单元2种细菌耐药能力均处于较高水平，随处理流程呈降低趋势，至消毒出水中不再被检出。长江中MCR-1携带菌耐粘菌素的半抑制浓度(EC50)较高，平均达37.89 mg·L-1，顺水流方向无显著降低。仅在下游朱家山河汇入口和长江大桥附近滨江公园检出较高耐药水平的NDM-1携带菌。2种细菌耐药水平受水体污染程度和人类活动影响较明显。自来水厂MCR-1携带菌数目较少，但其EC50平均可达32.75 mg·L-1，常规处理单元中未检出NDM-1携带菌。水处理工艺显著降低了细菌耐药水平，但排泥水中2种细菌均检出，且耐药水平相比进水显著提高。本研究可为评价水介质中超级抗性基因及其携带菌的环境风险提供参考。Abstract: To study the fates of super antibiotic resistant bacteria in surface water, represented by mobilized colistin resistance gene (MCR-1) and New Delhi metallo-β-lactamase-1 (NDM-1) hosting bacteria, the antibiotic resistance characteristics of the two classes of bacteria and their variation in the Yangtze River of Nanjing and nearby wastewater treatment plant (WWTP) and drinking water treatment plant (DWTP) were investigated. The results showed that the antibiotic resistance level of MCR-1 and NDM-1 hosting bacteria were both at high levels in the influent and biological treatment units of the WWTP. Then the antibiotic resistance level decreased along with the treatment process and no MCR-1 and NDM-1 hosting bacteria could be detected in the effluent. In Yangtze River, the MCR-1-hosting bacteria showed tolerance to rather high colistin level, with the average 50% effective concentration (EC50) of 37.89 mg·L-1, and no significant decrease of the EC50 value was detected along with the flow direction. NDM-1 hosting bacteria were not detected in the upstream, while high EC50 value of NDM-1 hosting bacteria was detected in the Zhujiashan River estuary and the Yangtze River Bridge (Park area). The antibiotic resistance level of the two bacteria was obviously affected by the degrees of water pollution and human activities. By comparison, fewer MCR-1 hosting bacteria were detected in the DWTP, but the level of colistin resistance was not low, with an average EC50 of 32.75 mg·L-1. No NDM-1 hosting bacteria was detected in the conventional treatment units of the DWTP. Water treatment process significantly reduced the level of bacterial resistance, while both bacteria were detected in the sludge with significantly higher level of antibiotic resistance comparing to the influent. The study can provide implications for assessing the environmental risks of super antibiotic resistance genes in aquatic environments.
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Key words:
- MCR-1 /
- NDM-1 /
- pollution characteristics /
- antibiotic resistance characteristics /
- influencing factors
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