摘要
      为了保护公众健康，抗生素耐药性基因（ARGs）在水生环境中的传播是一个新出现的问题。遏制ARGs在环境中的传播需要更好地了解水环境中ARGs的来源和驱动因素。在这项研究中，我们使用污水相关分子标记、1类整合素基因、标准水质参数和流域特征的直接测量来评估受人类活动梯度影响的城市流域ARGs的来源和驱动因素。定量聚合酶链式反应（qPCR）用于量化从佐治亚州亚特兰大市普罗克特溪流域采集的溪流水样中与污水相关的HF183、大肠杆菌粪便指示剂、1类整合素基因（int1）以及ARGs sulI、sulII、tetW、tetM、ampC和blaSHV的丰度。我们的研究结果表明，ARGs分布广泛，检测频率分别为96%（sulI和sulII）、82%（tetW和tetM）和49%（ampC和blaSHV）。所有ARGs均与HF183和大肠杆菌标记呈正相关（r>0.5）。使用广义增强开发的非线性机器学习模型表明，流域中超过70%的ARG负荷变化可以通过粪便源负荷来解释，其他因素如与获得性抗生素耐药性相关的1类整合子，以及环境因素对ARG变化的贡献小于30%。这些结果表明，在受到人为污染严重影响的水生环境中，来自粪便来源的输入比环境压力源或水平基因转移更能推动ARG的传播。最后，我们的研究结果为当地流域管理者和利益相关者提供了信息，以减轻城市溪流中ARGs和粪便细菌的负担。
Abstract
The spread of antibiotic resistance genes (ARGs) in the aquatic environment is an emerging concern in the interest of protecting public health. Stemming the environmental dissemination of ARGs will require a better understanding of the sources and drivers of ARGs in the water environment. In this study, we used direct measurement of sewage-associated molecular markers, the class 1 integron gene, standard water quality parameters, and watershed characteristics to evaluate the sources and drivers of ARGs in an urban watershed impacted by a gradient of human activities. Quantitative polymerase chain reaction (qPCR) was used to quantify the abundance of the sewage-associated HF183, the E. coli fecal indicator, class 1 integron gene (int1), and the ARGs sulI, sulII, tetW, tetM, ampC, and blaSHV in stream water samples collected from the Proctor Creek watershed in Atlanta, Georgia. Our findings show that ARGs were widely distributed, with detection frequencies of 96% (sulI and sulII), 82% (tetW and tetM), and 49% (ampC and blaSHV). All the ARGs were positively and significantly correlated (r > 0.5) with the HF183 and E. coli markers. Non-linear machine learning models developed using generalized boosting show that more than 70% of the variation in ARG loads in the watershed could be explained by fecal source loading, with other factors such as class 1 integron, which is associated with acquired antibiotic resistance, and environmental factors contributing < 30% to ARG variation. These results suggest that input from fecal sources is a more critical driver of ARG dissemination than environmental stressors or horizontal gene transfer in aquatic environments highly impacted by anthropogenic pollution. Finally, our results provide local watershed managers and stakeholders with information to mitigate the burden of ARGs and fecal bacteria in urban streams.

https://www.mdpi.com/2076-2607/10/9/1804