The cell envelope of bacteria as a target for chelant and antibiotic combinations

细菌的金属耐药性和抗生素耐药性越来越被认为是并行进化的过程。虽然不能很好地描述，但共耐药经常与细胞的进出口机制有关。事实上，一些抗生素会以金属络合物的形式主动转运到细胞内的靶点。因此，单独或一起扰乱金属和抗生素的吸收，为对抗日益耐药的病原体提供了巨大的潜力。该项目是与宝洁公司合作，使用具有不同选择性的金属螯合剂，成功地去除细菌病原体的基本金属。为了帮助确定两种具有不同金属物种亲和力的螯合剂的作用模式，我们分离了两种细菌物种的抗络合剂突变体，并从产生的菌株中鉴定了染色体的变化。发现了几个突变，影响了预期的金属吸收系统。然而，更多的突变被发现改变了细胞表面分子、膜结合的转运蛋白和参与肽聚糖新陈代谢的酶。有趣的是，对某些抗生素抗药性的提高在几个突变体中也很明显。此外，用螯合剂和抗生素的组合处理细菌发现了协同、相加和无差别的效果。因此，这些细菌的野生型和突变型衍生物为探索抗生素、金属螯合和细胞膜完整性之间的关系提供了一个极好的机会。该项目旨在了解螯合剂和抗生素是如何靶向和穿越细菌包膜的，并探索与金属摄取和耐受性的联系。通过更好地了解螯合剂如何抑制细菌生长，改进产品配方具有重大的商业前景。此外，它还提供了振兴现有抗生素的潜力，用于在医疗和兽医环境中治疗由重要的抗药性病原体引起的伤口。

Bacterial metal and antibiotic resistance are increasingly recognised as processes that evolve in parallel. Although not well-characterised, co-resistance is frequently associated with cellular import and export mechanisms. Indeed, some antibiotics are actively transported to their intracellular targets as metal complexes. Hence disrupting the uptake of both metals and antibiotics, either separately or together, offers significant potential to combat increasingly drug-resistant pathogens. This project emerges from successful efforts, in partnership with Procter & Gamble, to deprive bacterial pathogens of essential metals using metal chelants with differing selectivities. To help determine the mode of action of two chelants with affinities for different metallic species, we isolated chelant-resistant mutants of two bacterial species and identified chromosomal changes from the resulting strains. Several mutations were found that affected the anticipated metal uptake systems. However, additional mutations were identified that altered cell surface molecules, membrane-bound transporters and enzymes engaged in peptidoglycan metabolism. Interestingly, improved resistance to certain antibiotics was also evident in several of the mutants. Moreover, treating bacteria with combinations of chelants and antibiotics identified synergistic, additive and indifferent effects. The wild-type and mutant derivatives of these bacteria therefore provide an excellent opportunity to probe the relationship between antibiotics, metal chelation and cell envelope integrity. This project aims to understand how chelants and antibiotics target and traverse the bacterial envelope and explore links with metal uptake and tolerance. There are significant prospects commercially for improving product formulations through a better understanding of how chelants inhibit bacterial growth. Furthermore, it offers the potential to revitalise existing antibiotics for topical applications in the treatment of wounds, in both medical and veterinary contexts, caused by important antibiotic-resistant pathogens.