Mechanisms of antibiotic failure during osteomyelitis

骨髓炎期间抗生素失效的机制

• 批准号: 10737292
• 负责人: JAMES E CASSAT
• 金额: $ 57.71万
• 依托单位: VANDERBILT UNIVERSITY MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-01 至 2028-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10737292
• 关键词: Acute; Address; Agglutinins; Antibiotic Therapy; Antibiotics; Automobile Driving; Bacteria; Bacterial Infections; Binding; Blood coagulation; Cells; Characteristics; Childhood; Chronic; Clinical; Coagulase; Coagulation Process; Communicable Diseases; Coupled; Data; Debridement; Detection; Disease; Endowment; Etiology; Exposure to; Failure; Fibrin; Fibrinogen; Freezing; Genes; Genus staphylococcus; Goals; Growth; Histologic; Human; Immune; Immune response; In Situ; In Vitro; Infection; Integration Host Factors; Intervention; Invaded; Knowledge; Label; Link; Lipids; Measures; Membrane Proteins; Microscopy; Modality; Modeling; Morbidity - disease rate; Mus; Operative Surgical Procedures; Osteomyelitis; Pathogenesis; Patients; Pattern; Phenotype; Physiological; Population; Positioning Attribute; Predisposition; Procedures; Process; Proteins; Prothrombin; Protocols documentation; Reagent; Reporter; Role; Sampling; Serum; Specimen; Staphylococcus aureus; Staphylococcus aureus infection; Testing; Tissues; Treatment Efficacy; Treatment Failure; Virulence; Virulence Factors; antibiotic tolerance; bacterial community; bacterial genetics; bone; cohort; combat; experience; experimental study; genetic approach; genome-wide; improved; improved outcome; in vitro activity; in vivo; innovation; mass spectrometric imaging; microbial; molecular imaging; mouse model; mutant; novel; novel strategies; novel therapeutic intervention; pathogen; pathogenic bacteria; pharmacologic; small molecule; transposon sequencing; treatment duration

PROJECT SUMMARY / ABSTRACT Osteomyelitis is an invasive infection of bone most commonly caused by the bacterial pathogen Staphylococcus aureus. Successful treatment of osteomyelitis requires prolonged antibiotic treatment as well as invasive surgical procedures to remove infected and nonviable bone. Despite these aggressive measures, nearly 1 in 5 patients with osteomyelitis will fail treatment. This includes patients who receive antibiotics with proven in vitro activity against the causative pathogen. These observations position osteomyelitis as a paradigm for treatment-recalcitrant infection. The goal of this proposal is to define bacterial and host factors that contribute to antibiotic failure during osteomyelitis. We hypothesize that bacterial virulence factors and host responses that promote physical shielding of bacteria in vivo contribute to antibiotic tolerance. Upon successful completion of the proposed experiments, we expect to have defined targetable mechanisms underlying antibiotic failure during osteomyelitis, with the ultimate goal of maximizing treatment efficacy, minimizing complications, and creating new approaches to detect and combat antibiotic tolerance in humans. In preliminary studies using our established murine model of osteomyelitis, we demonstrate that S. aureus rapidly develops tolerance to antibiotic killing in vivo. Histologic analyses reveal a characteristic “pseudocapsule” surrounding bacterial communities in infected bone. Pseudocapsule formation is postulated to involve key virulence factors known as coagulases and agglutinins, which together endow S. aureus with its distinctive ability to coagulate blood. We hypothesize that these virulence factors contribute to antibiotic tolerance during osteomyelitis by physically shielding bacteria within host tissues. Aim 1 will rigorously test this hypothesis, while also identifying novel determinants of antibiotic tolerance using an unbiased, in vivo bacterial screen. We will track the relative localization of antibiotics and bacteria using innovative new S. aureus reporter strains coupled with fluorescent antibiotics. Aim 2 will test the complementary hypothesis that canonical host coagulation contributes to shielding of bacteria and antibiotic tolerance. This Aim will also employ our new workflow for imaging mass spectrometry (IMS) of bone, which will enable discovery-based profiling of host analytes that form antibiotic barriers in vivo. We will also leverage IMS as a modality for label-free tracking of antibiotics in infected tissues. Aim 3 will use paired bacterial isolates and serum samples from patients with osteomyelitis to test how growth in a physiologically relevant medium alters antibiotic killing, and to link in vitro antibiotic tolerance to key clinical parameters. Collectively, the experiments in this proposal will define mechanisms leading to antibiotic tolerance during osteomyelitis, paving the way for new interventions that improve antibiotic therapy, limit treatment failure, and reduce the morbidity of this debilitating disease.

项目概要/摘要 骨髓炎是一种最常见的由细菌病原体引起的骨侵袭性感染 金黄色葡萄球菌骨髓炎的成功治疗需要长期抗生素治疗。 尽管采取了这些积极的措施，但仍采用侵入性外科手术去除受感染和无法存活的骨头。 五分之一的骨髓炎患者治疗失败，其中包括接受经证实有效的抗生素的患者。 这些观察结果将骨髓炎作为一种范例。 该提案的目的是确定导致治疗难治性感染的细菌和宿主因素。 我们捕获了骨髓炎期间抗生素失效的细菌毒力因素和宿主反应。 促进体内细菌的物理屏蔽，有助于抗生素耐受性的成功完成。 在所提出的实验中，我们希望能够明确抗生素失败的可靶向机制 骨髓炎的最终目标是最大限度地提高治疗效果，最大限度地减少并发症，并创造 检测和对抗人类抗生素耐受性的新方法。 在使用我们建立的小鼠骨髓炎模型的初步研究中，我们证明了 S. 金黄色葡萄球菌在体内迅速产生对抗生素杀灭的耐受性。组织学分析揭示了一个特征。 假定感染骨中细菌群落周围有“假荚膜”。 涉及称为凝固酶和凝集素的关键毒力因子，它们共同赋予金黄色葡萄球菌 我们发现这些毒力因子有助于抗生素耐受。 在骨髓炎期间，通过物理屏蔽宿主组织内的细菌，目标 1 将严格检验这一假设， 同时还使用公正的体内细菌筛选来确定抗生素耐受性的新决定因素。 将使用创新的新金黄色葡萄球菌报告菌株追踪抗生素和细菌的相对定位 与荧光抗生素相结合，将检验典型宿主凝血的补充假设。 有助于屏蔽细菌和抗生素耐受性。该目标还将采用我们的新工作流程。 骨成像质谱 (IMS)，这将使基于发现的宿主分析人员分析成为可能 我们还将利用 IMS 作为无标记追踪感染者抗生素的模式障碍。 目标 3 将使用配对的细菌分离株和骨髓炎患者的血清样本来测试如何进行。 在生理相关培养基中的生长改变了抗生素的杀灭作用，并将体外抗生素耐受性与关键 总的来说，本提案中的实验将定义导致抗生素的机制。 骨髓炎期间的耐受性，为改善抗生素治疗的新干预措施铺平了道路，限制 治疗失败，并降低这种使人衰弱的疾病的发病率。