Emergence of TonB-dependent receptor mediated cefiderocol resistance among multidrug-resistant (MDR) Pseudomonas aeruginosa clinical isolates.

项目摘要 医疗保健相关病原体中抗生素耐药性的上升创造了公共卫生 这是对提供有效医疗服务的一个重大挑战。多重耐药（MDR） 铜绿假单胞菌被疾病控制和预防中心标记为严重威胁， 并且不成比例地影响医学上易受伤害的患者，例如重症监护室中的患者。的 出现对一线抗生素的耐药性，包括碳青霉烯类和最近引入的β-内酰胺/β- 内酰胺酶抑制剂组合，已导致使用替代方案，其功效降低， 毒性增加。头孢地罗可（FDC）是一种新型的铁载体头孢菌素， MDR-铜绿假单胞菌。这种抗生素模拟铜绿假单胞菌生长所需的铁结合分子， 通过细菌外膜上的蛋白质TonB主动转运到周质空间 依赖性受体（TBDR）。对FDC的耐药性与这些TBDR表达的缺失有关， 铜绿假单胞菌的临床分离株。此外，对在本发明之前收集的铜绿假单胞菌的基因组的分析显示， FDC的批准发现存在预测导致TBDR基因表达降低的突变 碳青霉烯类耐药菌株使用群体分析谱（PAP），几种铜绿假单胞菌菌株 具有TBDR突变的患者显示对FDC的异源耐药，或在抗生素浓度下小群细菌的生长 尽管对标准敏感性进行了敏感测试，但浓度仍高于临床耐药断点 试验.在两个主要的具体目标，这项建议将调查的假设，在TBDR基因突变， 存在于来自不同地理区域的铜绿假单胞菌临床分离株中， 暴露于FDC时的耐药性。在第一个目标中，将评估TBDR基因突变的患病率， 来自前瞻性观察性研究的近1000例碳青霉烯类耐药铜绿假单胞菌的集合 假单胞菌研究（POP）。该途径的改变将与FDC药敏试验结果相关， 使用PAP评估异源耐药性，以及铜绿假单胞菌定殖和感染的临床特征。在 第二个目标，我们将研究了解和减轻耐药性出现的策略 与TBDR突变有关。首先，将建立一种基于纸片扩散的鉴定异源耐药菌株的方法， 作为临床微生物实验室的筛选试验开发。第二，中空纤维感染模型 模拟FDC的人体药代动力学将用于评价FDC耐药性的出现， 临床相关药物浓度。该提案将提供有关分配和 铜绿假单胞菌中与FDC耐药相关的突变的患病率。开发了一种测定方法， 确定有耐药性风险的分离株，并了解耐药性出现的机制， 人体药物暴露，可以构成在患者床边合理使用FDC治疗的基础。

Project Summary The rise of antibiotic resistance among healthcare associated pathogens has created a public health emergency and is a major challenge to the provision of effective medical care. Multidrug-resistant (MDR) Pseudomonas aeruginosa is labeled as a serious threat by the Centers for Disease Control and Prevention, and disproportionately impacts medically vulnerable patients such as those in the intensive care unit. The emergence of resistance to front-line antibiotics, including carbapenems and recently introduced β-lactam/β- lactamase inhibitor combinations, has led to the use of alternate regimens with decreased efficacy and increased toxicity. Cefiderocol (FDC) is a novel siderophore cephalosporin that retains in vitro activity against MDR-P. aeruginosa. This antibiotic mimics the iron binding molecules P. aeruginosa requires for growth, and is actively transported into the periplasmic space by proteins on the outer membrane of the bacteria called TonB dependent receptors (TBDR). Resistance to FDC has been linked to a loss of expression of these TBDRs in clinical isolates of P. aeruginosa. Further, an analysis of genomes of P. aeruginosa collected before the approval of FDC found that mutations predicted to lead to decreased expression of TBDR genes were present in carbapenem-resistant isolates. Using population analysis profiles (PAP), several strains of P. aeruginosa with TBDR mutations showed heteroresistance to FDC, or growth of a small population of bacteria at antibiotic concentrations above the clinical resistance breakpoint despite testing susceptible on standard susceptibility testing. In two major specific aims, this proposal will investigate the hypothesis that mutations in TBDR genes are present across clinical isolates of P. aeruginosa from diverse geographic areas and lead to the emergence of resistance on exposure to FDC. In the first aim, the prevalence of TBDR gene mutations will be evaluated in a collection of nearly one thousand carbapenem-resistant P. aeruginosa from the Prospective Observational Pseudomonas study (POP). Alterations in this pathway will be linked to FDC susceptibility testing results, an assessment of heteroresistance using PAP, and clinical features of P. aeruginosa colonization and infection. In the second aim, we will investigate strategies to understand and mitigate the emergence of resistance associated with TBDR mutations. First, a disk diffusion-based method to identify heteroresistant isolates will be developed as a screening test for the clinical microbiology laboratory. Second, a hollow fiber infection model simulating human pharmacokinetics of FDC will be used to evaluate the emergence of FDC resistance at clinically relevant drug concentrations. This proposal will provide important information on the distribution and prevalence of mutations associated with resistance to FDC in P. aeruginosa. The development of an assay to identify isolates at risk of resistance, and an understanding of the mechanism by which resistance emerges at human drug exposures, can form the basis for rational therapeutic use of FDC at the patient bedside.