Abstract：
Metal nanoparticles (MNPs) have recently gained extensive attention due to their broad-spectrum prospect, particularly in biomedical application. Here, we reveal that long-term exposure to platinum nanoparticles (Pt NPs) increases the susceptibility of Pseudomonas aeruginosa PAO1 to imipenem and ciprofloxacin. We exposed PAO1 to Pt NPs (a series of doses, varying from 0.125 to 35 μg/mL) for 60 days and characterized the evolved strains (ES) and compared with wild type (WT) to understand the mechanism of heightened sensitivity. We found that overexpression of oprD and downregulation of mexEF-oprN facilitate the intracellular accumulation of antibiotic, thus increasing susceptibility. Furthermore, loss-of-function mutations were discovered in regulators lasR and mexT. Cloning intact lasR from wild-type (WT) into ES slightly improves imipenem resistance. Strikingly, cloning mexT from WT into ES reverts the imipenem and ciprofloxacin resistance to the original level. Briefly, the increase of membrane permeability controlled by mexT made PAO1 greatly susceptible to imipenem and ciprofloxacin, and the decrease of quorum sensing mediated by lasR made PAO1 slightly susceptible to imipenem. Overall, these results reveal an antibiotic susceptibility mechanism from prolonged exposure to MNPs, which provides a promising approach to prevent antibiotic resistance.
摘要：
金属纳米粒子(MNPs)由于其广谱的应用前景,近年来受到了广泛的关注,特别是在生物医学应用中。这里,我们发现，长期暴露于铂纳米颗粒（PtNPs）会增加铜绿假单胞菌PAO1对亚胺培南和环丙沙星的敏感性。我们将PAO1暴露于PtNP(一系列剂量，从0.125到35μg/mL）持续60天，并对进化菌株（ES）进行了表征，并与野生型（WT）进行了比较，以了解敏感性提高的机制。我们发现，oprD的过表达和mexEF-oprN的下调促进了抗生素的细胞内积累，从而增加敏感性。此外，在调节因子lasR和mexT中发现了功能丧失突变。将完整的lasR从野生型(WT)克隆到ES中略微改善亚胺培南抗性。引人注目的是，将mexT从WT克隆到ES中可以将亚胺培南和环丙沙星的抗性恢复到原始水平。简而言之，由mexT控制的膜通透性的增加使得PAO1对亚胺培南和环丙沙星非常敏感，lasR介导的群体感应降低使PAO1对亚胺培南略有敏感。总的来说,这些结果揭示了长期暴露于MNPs的抗生素敏感性机制，这提供了一种有希望的方法来防止抗生素耐药性。
