摘要

       生态系统通过废水、农业径流以及与动物相关的和人为活动不断暴露于各种抗菌素，这些活动有助于抗生素抗性基因 (ARG) 的传播。 ARGs 对生态系统的污染可能会增加它们向幼稚微生物转移的机会，并最终导致进入人类食物链。转导是自然环境中基因水平转移的重要机制，与转化相比，传统上被低估了。我们探索了环境噬菌体中 ARG 的存在，以确认它们对 ARG 在环境中传播的贡献。针对环境细菌分离物分离噬菌体，纯化并大量培养。对它们进行了表征，并通过 PCR 进行了 ARG 和 intI 基因的检测，包括 bla TEM、bla OXA-2、intI1、intI2、intI3、tetA 和 tetW。该研究揭示了各种基因的存在 [tetA (12.7 %)、intI1 (10.9 %)、intI2 (10.9 %)、intI3 (9.1 %)、tetW (9.1 %) 和 bla OXA-2 (3.6 %)] 和TEM 的比例要高得多（30.9 %）。在任何噬菌体中均未检测到 bla SHV、bla OXA-1、tetO、tetB、tetG、tetM 和 tetS。土壤噬菌体在 ARG 携带方面是最通用的。此外，tetA 的相对丰度与来源不同。与无组织的部门相比，来自有组织的农场的噬菌体显示出不同的 ARG，尽管 bla TEM ARG 的发生率没有显着差异。该研究反映了噬菌体在 ARGs 在环境库中传播中的作用，这可能为未来的临床相关耐药机制提供预警系统。

       The ecosystem is continuously exposed to a wide variety of antimicrobials through waste effluents, agricultural run-offs and animal-related and anthropogenic activities, which contribute to the spread of antibiotic resistance genes (ARGs). The contamination of ecosystems with ARGs may create increased opportunities for their transfer to naive microbes and eventually lead to entry into the human food chain. Transduction is a significant mechanism of horizontal gene transfer in natural environments, which has traditionally been underestimated as compared to transformation. We explored the presence of ARGs in environmental bacteriophages in order to recognize their contribution in the spread of ARGs in environmental settings. Bacteriophages were isolated against environmental bacterial isolates, purified and bulk cultured. They were characterized, and detection of ARG and intI genes including bla TEM, bla OXA-2, intI1, intI2, intI3, tetA and tetW was carried out by PCR. This study revealed the presence of various genes [tetA (12.7 %), intI1 (10.9 %), intI2 (10.9 %), intI3 (9.1 %), tetW (9.1 %) and bla OXA-2 (3.6 %)] and bla TEM in a significantly higher proportion (30.9 %). bla SHV, bla OXA-1, tetO, tetB, tetG, tetM and tetS were not detected in any of the phages. Soil phages were the most versatile in terms of ARG carriage. Also, the relative abundance of tetA differed significantly vis-à-vis source. The phages from organized farms showed varied ARGs as compared to the unorganized sector, although bla TEM ARG incidences did not differ significantly. The study reflects on the role of phages in dissemination of ARGs in environmental reservoirs, which may provide an early warning system for future clinically relevant resistance mechanisms.

https://www.microbiologyresearch.org/content/journal/jgv/10.1099/jgv.0.000639?crawler=true