Occurrence of sulfonamides and tetracyclines in the coastal areas of the Yangtze River (China) Estuary.

Antibiotics have attracted global attention due to the ecological risks to environment. In this paper, solid-phase extraction and ultra-performance liquid chromatography triple quadrupole mass spectrometry (LC-MS/MS) were utilized to analyze the fugitive characteristics of 10 antibiotics of sulfonamides (sulfadiazine, sulfamethazine, sulfadimidine, sulfathiazole, sulfapyridine, sulfamethoxazole) and tetracyclines (tetracycline, oxytetracycline, chlortetracycline and doxycycline) in the coastal waters and surfece sediments of the Yangtze River Estuary and the ecological risks of antibiotics in water were estimated using ecological risk assessment method. The results have showed that 7 of the 10 antibiotics were detected in the water, with total concentrations ranging from 0.652 to 434.47 ng/L. 8 antibiotics were detected in the sediment, with total concentrations ranging from 0.091 to 499.23 ng/g. The main antibiotic species detected in the sediment and water varied seasonally. Higher concentrations in spatially distributed areas where rivers meet and where human activities have a more significant impact. The ecological risks were found to be higher in spring and autumn than those in winter and summer. Spatial variation in individual microbial communities was not evident in the sediments. The relationship between antibiotics and microorganisms in the environment was predominantly positive. Physical and chemical factors were significantly correlated for both antibiotics and microbial communities. This study can provide research ideas for other types of antibiotics and provide a basis for the prevention of antimicrobial resistance (AMR).

[Distributions of Antibiotic Resistance Genes and Microbial Communities in the Nearshore Area of the Yangtze River Estuary].

Due to the extensive use of antibiotics, the resistance of microorganisms to antibiotics in the environment is increasing, and the problem of antibiotic resistance genes (ARGs) is becoming more and more severe, which seriously threatens ecological security and human health. In order to study the distribution characteristics of ARGs and the microbial community in different media in the coastal area of the Yangtze River Estuary, water and sediment samples from eight sites were collected through a field investigation. Two sulfonamide resistance genes ([STBX]sul1, sul2[STBZ]) and six tetracycline resistance genes (tetM, tetC, tetX, tetA, tetO, and tetQ), one integrase gene intI[STBX]1[STBZ], 16S rRNA gene, and the microbial community were detected and analyzed. The results showed that the detection rate of 10 resistance genes in the coastal area of the Yangtze River Estuary was 100%. [STBX]intI1[STBZ] was significantly positively correlated with various ARGs in the water samples. Proteobacteria and Bacteroidota were the dominant bacteria phyla in the water environment of the Yangtze River Estuary. Chloroplast was the main bacteria genus in water, and Chloroplast and Nitrospira were the main bacteria genera in sediment. In water, Nitrospirota was the common potential host of four tetracycline resistance genes (tetX, tetA, tetO, and tetQ). In sediments, Sva0485 was a potential host community shared by [STBX]sul1 and intI1[STBZ]. The distribution of the microbial community was an important factor affecting the migration and transformation of ARGs in the nearshore area of the Yangtze River Estuary.