Abstract
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.
Highlights
Antibiotic resistance genes (ARGs), emerging environmental contaminants, draw an increasingly attention due to their huge risk to human health (Pruden et al, 2006)
The floR, sulII, sulI, strB, strA, aadA, and tetS were identified as the prominent antibiotic resistance genes (ARGs) with the high detection frequencies ranging from 30.9 to 51.1%, suggesting a serious condition conferring resistance to tetracyclines, aminoglycosides, chloramphenicol, and sulfonamides in aquatic animals
Many previous studies mainly focused on sediments, water and aquatic animal gut microbiota (Khan et al, 2013; Fu et al, 2017; Gao et al, 2018), this study firstly reflected the occurrence of 37 ARGs conferring resistance to six classes of antibiotics in skin microbiota of aquatic animals from southeast coastal area of China, which provides a comprehensive profile on ARGs in microbiota of aquatic animals
Summary
Antibiotic resistance genes (ARGs), emerging environmental contaminants, draw an increasingly attention due to their huge risk to human health (Pruden et al, 2006). ARGs encoding resistance to a broad range of antibiotics have been found to be able to spread among bacteria via horizontal gene transfer (HGT), aggravating ARGs dissemination Especially human commensal bacteria and pathogens, have been reported to be multi-drug resistant (Hatha et al, 2005) and capable of transferring their resistance determinants among environmental bacteria of different genera (Agersø and Petersen, 2007; Guglielmetti et al, 2010), which results in a huge adverse effect to human health. The World Health Organization (WHO) pointed out that antibiotic resistance already had become one of the greatest threats to aquatic food and, global public health through the food chain
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