摘要

抗生素抗性基因（ARG）在环境中的传播是一个严重的问题。细菌ARG可以通过不同的移动遗传元件作为噬菌体颗粒进行扩散，从而形成新的环境传播载体。为了评估诸如暴雨或缺水等气候事件如何影响ARGs的传播，有必要了解它们在水生环境中的流行程度和丰度以及它们可能成为流动的潜在水库。这项研究评估了地中海河流水体和沉积物中ARGs的发生。通过qPCR对来自Llobregat河（NE西班牙）的69个水和70个沉积物样品的细菌和噬菌体级分中的6个临床相关的ARG（blaTEM，blaCTX-M，qnrA，qnrS，mecA和sul1）进行定量，雨季。 blaTEM和sul1是最普遍和最丰富的ARG;其他人则更加变化。观察到ARG流行率和丰度的显着季节性差异。由于在沉积物中检测到ARGs，在三种条件下评估了该沉积物中天然存在的最丰富的ARGs的持久性（blaTEM和sul1）。新鲜沉积物在14天内未发生ARG失活;而在半干燥和干燥的沉积物中，ARG在35天内下降不到2log10单位。 ARGs在水体和沉积物中的出现受季节条件的影响，可以被细菌和噬菌体颗粒调动。在沉积物中，ARG持续很长时间，因此沉积物可能是ARG的天然储库，从它们可以扩散并导致新的抗性品系出现。

The spread of antibiotic resistance genes (ARGs) in the environment is a serious concern. Bacterial ARGs can spread via different mobile genetic elements as phage particles, which thereby emerge as novel vectors for environmental dissemination. To assess how climate events, such as heavy rains or water scarcity, could affect the spread of ARGs, it is necessary to know their prevalence and abundance in aquatic environments as well as the potential reservoirs from which they could become mobile. This study evaluates the occurrence of ARGs in the water and sediment of a Mediterranean river. Six clinically relevant ARGs (blaTEM, blaCTX-M, qnrA, qnrS, mecA and sul1) were quantified by qPCR in the bacterial and phage fractions of 69 water and 70 sediment samples from the River Llobregat (NE Spain), collected during both dry and rainy periods. blaTEM and sul1 were the most prevalent and abundant ARGs; the others were more variable. Significant seasonal differences in ARG prevalences and abundances were observed. Since ARGs were detected in the sediment, the persistence of the most abundant ARGs naturally occurring in that sediment (blaTEM and sul1) was evaluated under three conditions. No ARG inactivation occurred in fresh sediment over 14 days; while the ARGs declined by less than 2 log10 units over 35 days in semi-dry and dry sediment. The occurrence of ARGs in water and sediment is influenced by seasonal conditions and they can be mobilized by bacteria and phage particles. In sediment, ARGs persist for long periods and hence sediment can be a natural reservoir of ARGs, from where they can spread and cause the emergence of new resistant strains.

https://www.sciencedirect.com/science/article/pii/S0269749116324010