摘要

       噬菌体是一种广泛分布的原核病毒，其数量比细菌还多。作为其生命周期的结果，噬菌体可以绑架宿主的部分遗传物质，包括抗生素抗性基因（ARGs），这些基因通过一个称为转导的过程释放噬菌体颗粒转移。ARGs在病原菌中的传播是目前严重的全球性健康问题。本研究以新鲜蔬菜（莴苣、菠菜、黄瓜）和农田土壤为研究对象，采用qPCR法对10种ARGs（blaTEM、blaCTX-M-1、blaCTX-M-9、blaOXA-48、blaVIM、mecA、sul1、qnrA、qnrS和armA）的病毒DNA片段进行了筛选。在大肠杆菌宿主菌株中进行繁殖试验之前和之后，分析噬菌体DNA中ARGs的存在，以评估噬菌体颗粒感染宿主的能力。在所有基质的噬菌体DNA片段中都发现了ARGs，尽管具有异质性。ARG在莴苣和土壤中的患病率显著高于其它作物，且以β-内酰胺酶最为常见。繁殖试验后，四种基质样品中的噬菌体颗粒中ARG密度均增加，证实部分分离的噬菌体颗粒具有传染性。本研究揭示了在蔬菜基质和农田土壤中含有大量游离的、可复制的含ARG噬菌体颗粒。这些颗粒被认为是在这些环境中进行耐药性转移的载体，在这些环境中它们可以持续很长时间，并有可能产生新的耐药菌株。摄取这些可移动的基因元素也可能有助于产生新的抵抗力，这是以前没有的风险。

         Bacteriophages are ubiquitously distributed prokaryotic viruses that are more abundant than bacteria. As a consequence of their life cycle, phages can kidnap part of their host's genetic material, including antibiotic resistance genes (ARGs), which released phage particles transfer in a process called transduction. The spread of ARGs among pathogenic bacteria currently constitutes a serious global health problem. In this study, fresh vegetables (lettuce, spinach and cucumber), and cropland soil were screened by qPCR for ten ARGs (bla_TEM, bla_CTX-M-1 group, bla_CTX-M-9 group, bla_OXA-48, bla_VIM, mecA, sul1, qnrA, qnrS and armA) in their viral DNA fraction. The presence of ARGs in the phage DNA was analyzed before and after propagation experiments in an Escherichia coli host strain to evaluate the ability of the phage particles to infect a host. ARGs were found in the phage DNA fraction of all matrices, although with heterogeneous values. ARG prevalence was significantly higher in lettuce and soil, and the most common overall were β-lactamases. After propagation experiments, an increase in ARG densities in phage particles was observed in samples of all four matrices, confirming that part of the isolated phage particles were infectious. This study reveals the abundance of free, replicative ARG-containing phage particles in vegetable matrices and cropland soil. The particles are proposed as vehicles for resistance transfer in these environments, where they can persist for a long time, with the possibility of generating new resistant bacterial strains. Ingestion of these mobile genetic elements may also favor the emergence of new resistances, a risk not previously.

         https://linkinghub.elsevier.com/retrieve/pii/S0160-4120(18)30048-5