Impact of Daptomycin Dose Exposure on Enterococci and Characterization of Resista

描述(由申请人提供)：由万古霉素耐药肠球菌(VRE)引起的感染与治疗选择有限和死亡率增加有关。达托霉素是一种新型脂肽类抗生素，具有抗VRE活性。然而，目前尚不清楚VRE用于优化患者预后和防止耐药出现的达托霉素剂量。长期目标是通过利用理想剂量暴露和确定与肠球菌对达托霉素耐药相关的表型和基因变化来优化和保存达托霉素治疗VRE感染的结果。这项研究的总体目标是确定达托霉素的剂量暴露断点(药代动力学/药效学[PK/PD]断点)和相关剂量，并确定已知的与金黄色葡萄球菌对达托霉素耐药相关的表型和基因变化是否也在肠球菌中发现。中心假设是，更高剂量的达托霉素将提供更大的杀菌活性，并防止出现耐药性。此外，在耐达托霉素的肠球菌中发现的表型和基因变化可能不同于金黄色葡萄球菌。这项拟议研究背后的理论基础是，关于达托霉素与肠球菌剂量关系的数据和对耐药机制的洞察将导致临床剂量优化，改善患者预后，减少耐药性的出现，并将达托霉素保留为临床上可行的抗生素。中心假设将通过追求两个具体目标来验证：1)使用分子定义的VRE临床菌株来确定达托霉素耐药的剂量暴露断点，以确定最佳剂量；以及2)从体外PK/PD模型中确定与达托霉素耐药肠球菌细胞膜和细胞壁相关的表型和遗传变化。在第一个目标下，将使用已建立的模拟心内膜赘生物的体外模型(之前针对动物心内膜炎模型进行验证)来确定使用不同临床剂量的达托霉素的断点(和相应的剂量)。在该模型中培育的达托霉素耐药菌株与达托霉素接触后，将检查细胞壁、细胞膜、基因序列和基因表达的变化。这项拟议的研究具有创新性，因为我们将利用体外PK/PD模型，该模型既模拟临床条件下的药物压力，又允许频繁评估生物体内的变化，以获得待研究的达托霉素耐药突变株。在本申请中提出的研究具有重要意义，因为它有望提供必要的知识，以了解肠球菌的耐药性特征及其与达托霉素剂量暴露的关系，从而导致剂量优化和改善患者预后。一旦这些知识可用，患者的预后将得到改善，达托霉素作为治疗肠球菌感染的可行治疗选择将得到保留。 公共卫生相关性：叙述保存可用于治疗多重耐药细菌感染的抗生素对公共卫生至关重要。对万古霉素耐药的肠球菌感染与死亡率增加有关，治疗选择有限。该项目的总体目标是确定用于肠球菌感染的达托霉素的最佳剂量，并增加对耐药机制的现有知识，这将使人们能够更好地了解和治疗这种传染病。

DESCRIPTION (provided by applicant): Infections caused by vancomycin resistant Enterococcus (VRE) are associated with limited treatment options and increased mortality. Daptomycin, a novel lipopeptide antibiotic, has activity against VRE. The daptomycin dose for VRE to optimize patient outcomes and prevent the emergence of resistance, however, is currently unknown. The long-term goal is to optimize outcomes and preserve daptomycin therapy for VRE infections through utilization of the ideal dose exposure and determination of phenotypic and genotypic changes associated with daptomycin resistance in enterococci. The overall objective of this study is to define the dose exposure breakpoint (pharmacokinetic/pharmacodynamic [PK/PD] breakpoint) for daptomycin and the correlating dose and determine if known phenotypic and genotypic changes associated with daptomycin resistance in S. aureus are also found in enterococci. The central hypothesis is that higher daptomycin doses will provide greater bactericidal activity and prevent the emergence of resistance. Additionally, phenotypic and genetic changes found in daptomycin resistant enterococci maybe different than those found in S. aureus. The rationale behind the proposed research is that data on the daptomycin dose relationship with enterococci and insights into the mechanisms of resistance will lead to clinical dose optimization, improved patient outcomes, reduced emergence of resistance, and preservation of daptomycin as a viable antibiotic for clinical use. The central hypothesis will be tested by pursuing two Specific Aims: 1) Determine the dose exposure breakpoints for daptomycin resistance using molecularly defined and clinical strains of VRE to determine the optimal dose; and 2) Identify phenotypic and genetic changes associated with the cytoplasmic membrane and the cell wall of daptomycin resistant enterococci derived from in vitro PK/PD models. Under the first aim, a well established in vitro model of simulated endocardial vegetations (previously validated against an animal endocarditis model) will be used to determine the breakpoints (and corresponding doses) utilizing various clinical doses of daptomycin. The daptomycin resistant strains developed in this model with daptomycin exposure will then be examined for changes in the cell wall, cytoplasmic membrane, gene sequences and gene expression. The proposed research is innovative because we will utilize an in vitro PK/PD model, which both simulates drug pressure under clinical conditions and allows for frequent assessment of changes in the organism, to derive the daptomycin resistant mutants to be studied. The research proposed in this application is significant because it is expected to provide the knowledge needed to understand the resistance characteristics of enterococci and their relationship to daptomycin dose exposure that will lead to dose optimization and improved patient outcomes. Once such knowledge is available, improved patient outcomes and the preservation of daptomycin as a viable therapeutic option for the treatment of enterococcal infections will result. PUBLIC HEALTH RELEVANCE: Narrative Preservation of available antibiotics to treat multidrug resistant bacterial infections is vital to public health. Vancomycin resistant enterococcal infections are associated with increased mortality and treatment options are limited. The overall goal of this project is to determine the optimal dose of daptomycin for enterococcal infections and increase current knowledge of the mechanisms of resistance, which will allow better understanding and treatment of this infectious disease.