污水河道污泥中大肠杆菌抗生素抗性与金属耐受性的耦合分析

城市污水河道受人为活动的影响，可能作为抗性细菌与抗性基因的储库，给人类生产生活带来巨大的威胁.本研究以中国寒区城市污水河道污泥为取样点，研究大肠杆菌（Escherichia coli）的抗生素与金属的耐药现状，以评估中国寒区城市水环境受抗性细菌污染的情况与传播抗性的风险.利用选择性培养基从河道淤泥中分离出455株肠杆菌，并从中筛选出110株E. coli.抗生素表型结果显示：69.1%的E. coli分离株对至少1种抗生素具有抗性，其中，抗性最高的是氧四环素（42.7%）；所有的E. coli对亚胺培南和呋喃妥因没有抗性；分离株E. coli DL27对检测的17种抗生素中的13种具有抗性，分离株E. coli DL18、分离株E. coli DL46对12种抗生素具有抗性.金属抗性表型检测结果显示：40.9%的E. coli对银（Ag）具有耐受性，3.6%的分离株对汞（Hg）、锌（Zn）具有耐受性，所有菌株对铜（Cu）无耐受性；且发现分离株E. coli DL35对9种抗生素和2种金属具有抗性.对E. coli群体15种抗生素抗性基因（Antibiotic Resistance Genes，ARGs）、4种金属耐受性基因（Metal Resistance Genes，MRGs）、1种整合酶基因的检测结果显示，ARGs中tetA（56.4%）、blaTEM（26.4%）、sul2（24.5%）、sul1（22.7%）基因的检出率最高，MRGs的检出率分别为20.0%（silB）、13.6%（silE）、8.2%（merC）、16.4%（pcoE），整合酶基因intI1的检出率为2.7%.研究表明，在河道污泥中不仅存在多重抗生素抗性E. coli，而且存在同时具有抗生素抗性和金属耐受性的E. coli.河道污泥是抗性细菌和抗性基因的储库，对人类生产生活构成了潜在的巨大威胁.

Antibiotic resistance and metal resistance of Escherichia coli isolated from the urban sewage channel

The urban sewage channel may present a great threat to humans as reservoirs of resistant bacteria and resistance genes because it is mainly affected by human activities. To explore the effects of human activities on bacterial resistances, samples from an urban sewage channel in Northeast China were collected to investigate the antibiotic resistances and metal resistances of Escherichia coli (E. coli). Four hundred and fifty-five bacterial strains belonging to Enterobacteriaceae were isolated using the selective media, of which 110 E. coli strains were identified. The results of 17 antibiotic phenotypic resistances showed that 69.1% of the E. coli isolates were resistant to the antibiotic. The highest percentage of resistance was to oxytetracycline (42.7%). None was resistant to imipenem and nitrofurantoin. The isolate E. coli DL27 was resistant to 13 antibiotics. And isolate E. coli DL18 and E. coli DL46 were resistant to 12 antibiotics. For the metal resistances, 40.9% of the isolates were resistant to Ag, 3.6% resistant to Hg and Zn. None is resistant to Cu. Of all isolates, 27.3% were resistant to at least one antibiotic and one metal. Isolate E. coli DL35 was even resistant to nine antibiotics and two metals. Fifteen antibiotic resistance genes (ARGs), four metal resistance genes (MRGs) and one integrase gene were detected. The results showed that for ARGs, tetA (56.4%), blaTEM (26.4%), sul2 (24.5%) and sul1 (22.7%) were found. For MRGs, the percentages were 20.0% (silB), 13.6% (silE), 8.2% (merC), and 16.4% (pcoE), respectively. The percentage of the integrase gene intI1 was only 2.7%. These results indicated that there not only existed multi-antibiotic resistant E. coli strains, but also detected a combination of antibiotic resistances and metal resistances. The sewage channel as a reservoir for resistant bacteria could bring a great threat for human health.