摘要

       环境中抗生素抗性基因 (ARG) 的转移对人类和动物健康都构成威胁。然而，很少探讨噬菌体通过转导传播抗性基因的作用。在这项研究中，我们从中国三个商业农场的猪粪便中筛选出 32 种临床相关的 ARG 类型，以评估细菌和噬菌体中 ARG 种群的存在，并进一步估计噬菌体对抗生素耐药性传播的贡献。我们发现噬菌体 DNA 含有 35.5% 的目标 ARG 类型，并且在 100% 的噬菌体 DNA 样本中发现了 sul1、blaTEM 和 ermB。细菌种群中最丰富的基因是 ermB 和 fexA，而 ermB 在噬菌体中最丰富。相比之下，floR 是两个种群中含量最少的 ARG。此外，本研究首次使用噬菌体和细菌中ARGs丰度的比率指数作为噬菌体传播ARGs能力的估计量。 qnrA 的比率最大（约 10-1），与最丰富的噬菌体 ARG ermB 不同。此外，fexA 的比率值最低（约 10-6），而不是 floR。这些结果说明单独使用ARGs丰度和检出率可能不适合综合判断噬菌体对抗生素耐药性传播的贡献。一个更合适的模型是三个指标的应用；发生率、噬菌体的绝对丰度和作为噬菌体环境 ARG 评估的警告和监测工具的比率值。

       The transfer of antibiotic resistance genes (ARGs) in the environment is a threat to both human and animal health. However, the contribution of bacteriophages to the dissemination of resistance genes via transduction is rarely explored. In this study, we screened pig feces from three commercial farms in China for 32 clinically relevant ARG types to assess the presence of the ARG population in bacteria and bacteriophage and further to estimate the contribution of bacteriophages to the dissemination of antibiotic resistance. We found that bacteriophage DNA contained 35.5% of the target ARG types and sul1, blaTEM and ermB were found in 100% of the phage DNA samples. The most abundant genes in the bacterial population were ermB and fexA whereas ermB was the most abundant in bacteriophage. In contrast, floR was the least abundant ARG in both populations. Also, the ratio index of the abundance of ARGs in bacteriophage and bacteria was firstly used in this study as an estimator of bacteriophage ability to transmit ARGs. The ratio for qnrA was the greatest (about 10−1) and differed from the most abundant bacteriophage ARG ermB. In addition, fexA had the lowest ratio value (about 10−6) and not floR. These results illustrate that ARGs abundance and detection rates used alone probably be not suitable for comprehensively judging the contribution of bacteriophage to the dissemination of antibiotic resistance. A more suitable model is the application of three indices; occurrence rate, absolute abundance in bacteriophage and the ratio value as warning and monitoring tools for environmental ARG assessments in bacteriophages.

https://www.sciencedirect.com/science/article/abs/pii/S0269749117349187