Characteristics of antibiotics and antibiotic resistance genes in Qingcaosha Reservoir in Yangtze River Delta, China

Abstract

Background Aquatic ecosystems are considered to be among the most important reservoirs of antibiotic resistance genes (ARGs). Drinking water sources were usually parts of lakes and rivers in Yangtze River Delta, among which Qingcaosha Reservoir is the largest river impoundment and benefit the population of more than 13 million for Shanghai city. In this study, we aimed at investigating the distribution of antibiotics and ARGs to characterize the pollution across various sites in Qingcaosha Reservoir in three seasons. Results Sulfamethoxazole, sulfamonomethoxine and penicillin G potassium salt were the dominant antibiotics and of high detection frequencies in this reservoir. Sulfonamide resistance genes ( sul1 and sul2 ) were the most prevalent and predominant genes. Higher total relative abundance of the ARGs were detected in the site closest to the inflow than those in other sites. Overall, the concentrations of antibiotics in May (spring) were relatively lower than November (autumn) and February (winter). Correlation analysis indicated sul1 , ermB and mphA had positive correlation with corresponding antibiotics in February and intI1 was also greatly positively correlated to sul1 , sul2 , ermB and mphA . Conclusion In conclusion, the antibiotics and ARGs were widespread in Qingcaosha Reservoir. Our result indicated that the drinking water reservoir might serve as gene reservoir for antibiotic resistance and mobile gene element intI1 can serve as a medium to contribute to the widespread of various ARGs. What is more, we considered that Reservoir could be served as a functional area contributing to the elimination of ARGs.