There is a growing concern about the role of the environment in the dissemination of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARG). In this systematic review, we summarize evidence for increases of ARG in the natural environment associated with potential sources of ARB and ARG such as agricultural facilities and wastewater treatment plants. A total of 5247 citations were identified, including studies that ascertained both ARG and ARB outcomes. All studies were screened for relevance to the question and methodology. This paper summarizes the evidence only for those studies with ARG outcomes (n= 24). Sixteen studies were at high (n= 3) or at unclear (n= 13) risk of bias in the estimation of source effects due to lack of information or failure to control for confounders. Statistical methods were used in nine studies; three studies assessed the effect of multiple sources using modeling approaches, and none reported effect measures. Most studies reported higher ARG concentration downstream/near the source, but heterogeneous findings hindered making any sound conclusions. To quantify increases of ARG in the environment due to specific point sources, there is a need for studies that emphasize analytic or design control of confounding, and that provide effect measure estimates.

中文翻译：

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点源对自然环境中抗生素抗性基因的影响：对证据的系统评价

人们越来越关注环境在抗生素抗性细菌 (ARB) 和抗生素抗性基因 (ARG) 传播中的作用。在本系统评价中，我们总结了与 ARB 和 ARG 的潜在来源（如农业设施和废水处理厂）相关的自然环境中 ARG 增加的证据。共确定了 5247 条引用，包括确定 ARG 和 ARB 结果的研究。所有研究都进行了筛选，以确定与问题和方法的相关性。本文仅总结了那些具有 ARG 结果的研究的证据（n= 24)。十六项研究处于高水平（n= 3) 或不清楚 (n= 13) 由于缺乏信息或无法控制混杂因素，源效应估计存在偏差的风险。九项研究使用了统计方法；三项研究使用建模方法评估了多种来源的影响，但没有一项研究报告了影响措施。大多数研究报告了下游/附近源的 ARG 浓度较高，但异质性的发现阻碍了做出任何合理的结论。为了量化由于特定点源导致的环境中 ARG 的增加，需要进行强调分析或设计控制混杂并提供效果测量估计的研究。