Distribution Characteristics of Sulfonamide Antibiotic Resistance Genes in a Drinking Water Source in East China

Abstract

Antibiotic resistance genes (ARGs) in drinking water sources have attracted widespread attention due to the threat they pose to water security and human health. This study mainly focused on the distribution of sulfonamide ARGs (sul 1, sul 2) and one integrase gene (intI 1) in water and sediment using qualitative and fluorescent quantitative PCR, based on previous work on the characteristics of 13 kinds of sulfonamides in a drinking water source in East China. Results showed that the three target genes were all detected in water and sediment. The sul 1 gene was the sulfonamide ARG with highest concentration, with 1.5×104-6.4×105 copies·mL-1 in source water and maximum concentration of 1.6×108 copies·g-1 in sediment. Concentration of sul 1 was 0.6-2.2, 0.5-1.9 order of magnitudes higher than sul 2 and intI 1 genes, respectively. There was no significant difference between the absolute concentrations of sul 1, sul 2, and intI 1 in inflow and outflow. However, in the case of sediment, absolute abundances of sul 1, sul 2, and intI 1 in outflow were higher than those in inflow. The maximum concentration of sul 1 was detected in outflow in summer (6.4×105 copies·mL-1). The concentration of intI 1 was higher in winter compared to other seasons. There was a positive correlation between sul 1 and 13 sulfonamides (r=0.69, P<0.05), and the relative concentration of sul 1 and amount of sulfamethoxazole were significantly positively related (r=0.79, P<0.01). There were also positive correlations between the relative concentrations of intI 1 and sul 1, sul 2 (r:0.80 and 0.73, P<0.05), respectively, suggesting that intI 1 played an important role in horizontal gene transfer of sulfonamide ARGs in this drinking water source. This study provides basic data for monitoring pollution of ARGs, as well as a basis for controlling ARG pollution in the drinking water environment and making management decisions.