Occurrence and distribution of antibiotic resistance genes in the water and sediments of Qingcaosha Reservoir, Shanghai, China

Qingcaosha Reservoir is China’s largest river impoundment and an important drinking water resource for Shanghai city. Although antibiotics contamination in the reservoir has been reported, little is known about the presence of antibiotic resistance genes (ARGs). In this study, the occurrence and distribution of 12 ARGs and the class 1 integron gene (intI-1) in water and sediments collected from the reservoir were investigated for 1 year. The 12 ARGs were detected in both water and sediment samples, and no significant temporal or spatial variations were observed. Sulfonamide resistance genes were predominant in the reservoir with a detection frequency of 100%. Statistical analysis indicated a positive correlation in relative abundance between some ARGs such as sul1, sul2, and intI-1. Most ARGs were negatively correlated with total nitrogen and positively correlated with chemical oxygen demand and chlorophyll-a. In general, ARGs were found to be prevalent in Qingcaosha Reservoir, among which sulfonamide resistance genes were the most dominant and tetB was the least. intI-1 may facilitate the proliferation and propagation of some ARGs, especially sul1 and sul2. The abundance of ARGs was well correlated with aquatic environmental factors in water, providing potential clues for the control of ARG contamination.