Occurrence, risk assessment of antibiotics and antimicrobial resistance in Escherichia coli in typical rivers of Sichuan

Worldwide interest has been generated by the presence and distribution of antibiotics and antibiotic resistance genes (ARGs) in rivers. However, there was a dearth of research on the contamination of Sichuan provinces typical rivers with antibiotics. In this study, the residual level of antibiotics in 42 national/provincial sites of 9 rivers was analyzed by UPLC-MS/MS, the ecological risk level was evaluated using risk assessment method, and the drug resistance of E. coli in water was evaluated by Kirby-Bauer method. Redundancy analysis demonstrated how residual antibiotics affect the structure of the microbial community in the Minjiang River basin (RDA). Nine rivers all contained antibiotics. Among them, the MinJiang, TuoJiang, and JiaLingJiang rivers were severely contaminated with antibiotic concentrations ranging from 0.29 to 2233.71 ng/L. The Sichuan Basins antibiotic pollution level was significantly higher when compared to other Sichuan zones, which was consistent with the regions high population density. Additionally, it was discovered that 9.77% of the E. coli isolated from 9 rivers had antibiotic resistance, and more than 5.8% of them had multidrug resistance. Moreover, Norfloxacin, amoxicillin, ampicillin, and tetracycline were the main risk factors for high ecological risk in 26 of the 42 monitoring sites. Additionally, there is a strong correlation between the microbial community change and residual antibiotic. These results offered some reference information regarding the distribution of antibiotics and ARGs in typical rivers in the Chinese province of Sichuan, and this study showed that more attention needs to be paid to antibiotic pollution in Sichuans typical rivers.