摘要

       抗生素耐药基因（ARGs）作为一种新的污染物的出现，一直是人类健康关注的问题。水产养殖中使用的抗生素促进了ARGs的进化和传播。本研究旨在调查中国东南沿海5个城市94种水生动物对6类抗生素耐药的37种ARGs的发生情况。结果表明，floR、sulII、sulI、strB、strA、aadA和tetS是检出率在30.9%～51.1%之间的重要ARGs。然后用qPCR定量7个显著ARGs的相对表达量，范围为0.003～0.065。在七个ARG中，tetS是最丰富的ARG。aadA虽然是ARGs的第二高检测频率，但却是ARG的最低表达量。淡水水生动物中ARGs的出现率和丰度均高于海洋动物，反映了淡水养殖与海洋养殖模式的差异。上海被认为是最常见的地点，有16个ARGs，宁波仅含有9个ARGs，没有β-内酰胺ARGs和喹诺酮类ARGs，显示ARGs随地理位置的变化。进一步测定了上海地区8种磺胺类药物和1种氯霉素残留量。有趣的是，没有发现靶向抗生素，但是磺胺类药物耐药基因（sulI，sulII）和氯霉素耐药基因（floR）在没有选择压力的情况下仍然存在于水生动物体内。本研究首次对水生动物皮肤微生物群中的ARGs进行了全面的研究，为更好地了解ARGs在水生动物中的传播提供了有用的信息和新的视角。

       The occurrence of antibiotic resistance genes (ARGs) as emerging contaminants is of continued concern for human health. Antibiotics used in aquaculture have promoted the evolution and spread of ARGs. This study aimed to investigate the occurrence of 37 ARGs conferring resistance to six classes of antibiotics in 94 aquatic animals from five cities in southeast coast of China. The results showed that floR, sulII, sulI, strB, strA, aadA, and tetS were identified as the prominent ARGs with the high detection frequencies ranging from 30.9 to 51.1% in total samples. Then relative expression amount of seven prominent ARGs quantified by qPCR, ranging from 0.003 to 0.065. The tetS was the most abundant ARG among the seven ARGs. Though aadA was the second highest detection frequency of ARGs, it was the lowest expression amount ARG. The occurrences and abundances of ARGs in freshwater aquatic animals were greater than those in marine, reflecting the discrepancy of cultivation pattern between the freshwater and marine aquaculture. Shanghai was considered as the most prevalent site with 16 ARGs, and Ningbo merely contained 9 ARGs without of β-lactam ARGs and quinolone ARGs, showing variations of ARGs with geographical location. Eight kinds of sulfonamides and one chloramphenicol residues were further measured in samples from Shanghai. Interestingly, no target antibiotics were found, but sulfonamides resistance genes (sulI, sulII) and chloramphenicol resistance genes (floR) persisted at aquatic animals in the absence of selection pressure. Our research firstly shows comprehensive information on the ARGs in skin microbiota of aquatic animals, which could provide useful information and a new insight for better understanding on the ARGs dissemination in aquatic animals.

       https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6070771/