Tetracyclines, sulfonamides and quinolones and their corresponding resistance genes in coastal areas of Beibu Gulf, China.

As the rapid development of aquaculture in the Beibu Gulf, large number of antibiotics was released into marine aquatic environment. But little integrated studies concerned on the occurrence and correlation of antibiotics with their corresponding ARGs in this region. We investigated the abundance of three prevalent categories of antibiotics and corresponding antibiotic resistance genes (ARGs), analyzed the potential correlation among antibiotics, ARGs and sediment properties in eight terminal rivers, nine semi-closed sites and eight nearshore areas from Beibu Gulf. Residual concentrations of total antibiotics ranged from 51.04 to 137.64 μg/kg, TETs had higher concentrations than FQs and SAs. Conventional PCR of ARGs revealed intI1, sul2, tetB, tetC and tetG had 100% detection frequency in all samples. Quantitative analysis showed sul genes were dominant compared to tet genes. The abundance of antibiotics and ARGs were decreased from river to open sea. Significant correlations (p < .05) between intI1 and ARGs (sul2 and tetG) were revealed by Pearson analysis, indicating that intI1 gene played a significant role in the occurrence and diffusion of ARGs. Significant correlations among the ARGs, the corresponding or irrelevant residual antibiotics and sediment characteristics were observed by redundancy analysis and network. Due to the potential health risks of antibiotics with corresponding ARGs, the control and treatment measures should deserve wide attention.