Prevalence, Consequences and Mechanisms of Antibiotic Heteroresistance in Cystic Fibrosis

项目摘要 改善感染结果的进展取决于了解减少抗生素作用的因素。 最近的研究表明，抗生素的异质耐药性可能是一个关键因素。异源抗性病原体表现出 群体水平的抗性异质性，这意味着它们含有高抗性亚群， 表现出不稳定的抗性，这意味着一些细胞在没有抗生素的情况下生长时会迅速变得敏感。 这一建议的重点是这两个表型，因为他们被假定有重大影响的易感性 测试和抗生素功效。在这里，我们建议研究群体水平的耐药性异质性， 囊性纤维化（CF）和慢性铜绿假单胞菌（Pa）患者的耐药性不稳定 周期性吸入妥布霉素的感染。 CF为这些研究提供了关键优势，因为它是一种具有统一表现的单基因疾病， 单一细菌物种对相同抗生素的反应可以在相当大的群体中进行研究， 在抗生素“开”期间，存在从感染部位（痰）采集原始标本的基础设施， “关”的时期。这些优势，以及我们在前期工作中开发的方法，使我们能够测试 来自慢性感染患者的Pa表现出明显的群体水平耐药异质性的假设 和不稳定的抵抗力;说明这些因素的参数预测对治疗的临床反应; CF Pa的不稳定抗性是由于一组核心基因扩增和适应性补偿 点突变这项工作将产生关于抗生素异质耐药性的基础知识， 提高对CF抗生素治疗失败的理解，并提出新的精确医学方法， 选择抗生素并改善结果。这些发现也可以指导未来的感染工作， 异质性、病原体和治疗方法多样性以及基础设施欠发达使得研究更加困难。

Project Summary Progress in improving infection outcomes depends upon understanding factors that diminish antibiotic action. Recent work suggests antibiotic heteroresistance may be a key factor. Heteroresistant pathogens exhibit population-level resistance heterogeneity, meaning they contain highly resistant subpopulations, and often exhibit unstable resistance, meaning some cells become rapidly sensitive when grown without antibiotics. This proposal focuses on these two phenotypes as they are postulated to have major effects on susceptibility testing and antibiotic efficacy. Here we propose to study population-level resistance heterogeneity and unstable resistance in people with cystic fibrosis (CF) and chronic Pseudomonas aeruginosa (Pa) infections who cycle on and off inhaled tobramycin. CF offers key advantages for these studies as it is a monogenic disease with uniform manifestations, the responses of a single bacterial species to the same antibiotic can be studied in sizable cohorts, and infrastructure exists to procure primary specimens from the infected site (sputum) during antibiotic "on" and "off" periods. These advantages, and methods developed in our preliminary work enable us to test the hypotheses that Pa from chronically-infected patients exhibit marked population-level resistance heterogeneity and unstable resistance; that parameters accounting for these factors predict clinical responses to treatment; and that unstable resistance in CF Pa is due to a core set of gene amplifications and fitness-compensating point mutations. This work will generate foundational knowledge about antibiotic heteroresistance that could improve understanding of antibiotic treatment failure in CF, and suggest new precision medicine approaches to select antibiotics and improve outcomes. The findings could also guide future work in infections where patient heterogeneity, pathogen and treatment diversity, and less developed infrastructure make studies more difficult.