Determination of the antibiotic and antibiotic resistance footprint in surface water environment of a metropolitan area: Effects of anthropogenic activities

This study investigated geospatial distributions of antibiotics and antibiotic resistance genes (ARGs) in surface waters and their associations with anthropogenic activities. During July‒October 2020, the concentrations of antibiotics (water and sediment) and ARGs (sediment) were measured at 39 sites in the Twin Cities metropolitan area (Minnesota) that experience a gradient of impacts related to human activities. For water samples, the number of antibiotics detected and the concentrations of certain antibiotics (e.g., sulfonamides) positively correlated with urbanization indicators (e.g., urban percentage, population density, number of wastewater discharge points; ρ =0.32‒0.46, p =0.003‒0.04) and negatively correlated with undeveloped land indicators (e.g., forest; ρ =-0.34‒-0.62, p =0.00001‒0.04). Antibiotics in sediments exhibited geospatial distribution different from that in corresponding water samples and exhibited no associations with anthropogenic factors. Relative abundances of ARGs were not associated with anthropogenic factors, but several ARGs (e.g., blaoxa, mexB, and sul2) were inversely related to the organic content of sediments (ρ =-0.38‒-0.44, p =0.01‒0.04). Strong correlations were found among relative abundances of various ARGs and intI1 (ρ ≥ 0.67, p 0.05), highlighting their co-occurrence in (sub)urban surface waters. These results identified promising anthropogenic/environmental factors for predicting antibiotic geospatial distributions and useful gene markers to monitor ARGs in surface waters.

本研究探究了地表水中抗生素及抗生素抗性基因（ARGs）的地理空间分布特征，及其与人为活动的关联。2020年7月至10月期间，研究人员在双子城大都市区（明尼苏达州）的39个采样点测定了抗生素（水体和沉积物）及ARGs（沉积物）的浓度，这些采样点受人为活动影响的程度呈梯度变化。对于水样而言，检出的抗生素种类数及特定抗生素（如磺胺类药物）的浓度与城市化指标（如城市用地占比、人口密度、废水排放点数量；ρ=0.32‒0.46，p=0.003‒0.04）呈正相关，与未开发土地指标（如森林；ρ=-0.34‒-0.62，p=0.00001‒0.04）呈负相关。沉积物中的抗生素地理空间分布与对应水样存在差异，且与人为因素无显著关联。ARGs的相对丰度与人为因素无关，但部分ARGs（如blaoxa、mexB、sul2）与沉积物有机质含量呈负相关（ρ=-0.38‒-0.44，p=0.01‒0.04）。多种ARGs的相对丰度与intI1之间存在强相关性（ρ≥0.67，p<0.05），表明它们在（半）城市地表水中共存。这些结果识别出可用于预测抗生素地理空间分布的潜在人为/环境因素，以及监测地表水中ARGs的有效基因标志物。