Determining the value of PBP 7/8 as an antimicrobial target for XDR-A. baumannnii

确定 PBP 7/8 作为 XDR-A 抗菌靶点的价值。

• 批准号: 9888955
• 负责人: THOMAS A RUSSO
• 金额: --
• 依托单位: VA WESTERN NEW YORK HEALTHCARE SYSTEM
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-10-01 至 2023-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9888955
• 关键词: Abscess; Acinetobacter baumannii; Active Sites; Acute; Affect; Anti-Bacterial Agents; Antimicrobial Resistance; Ascites; Attention; Bacillus; Binding; Biological Assay; Carbapenems; Ceftazidime; Cells; Cellular Structures; Characteristics; Complement; Cytolysis; Data; Development; Drug Targeting; Drug resistance; ESKAPE pathogens; Elements; Endopeptidases; Escherichia coli; Generations; Goals; Growth; Health; Health Care Costs; Healthcare; Host Defense; Human; In Vitro; Incidence; Infection; Insecta; Laboratories; Location; Long-Term Care; Mediating; Meropenem; Methods; Microbial Biofilms; Military Personnel; Modeling; Molecular Weight; Monoclonal Antibodies; Monoclonal Antibody Therapy; Morbidity - disease rate; Muramidase; Pathogenicity; Penicillin-Binding Proteins; Penicillins; Peptidoglycan; Performance; Permeability; Pneumonia; Population; Predisposition; Prevention approach; Process; Production; Rattus; Reporting; Research Personnel; Resistance; Resistance development; Salmonella; Serum; Specificity; Structure; Subcutaneous abscess; Tazobactam; Testing; Tobramycin; Veterans; Work; antimicrobial; antimicrobial drug; assay development; bactericide; base; capsule; cost; drug development; drug resistant pathogen; extensive drug resistance; high throughput screening; in vivo; inhibitor/antagonist; insight; molecular mass; mortality; novel strategies; pathogen; periplasm; preclinical study; resistant strain; small molecule; small molecule libraries; tool; trait; transposon sequencing

Anticipated Impacts on Veterans Health Care. The incidence of infections due to highly resistant Acinetobacter baumannii is increasing. True pan drug resistant (PDR) strains have been reported. Unfortunately, the newly approved antimicrobials ceftolozane-tazobactam, ceftazidime-avibactam, and meropenem/vaborbactam are poorly active against resistant A. baumannii. The need to identify new antimicrobials active against A. baumannii is pressing. Background. We have demonstrated that the A. baumannii low molecular mass (LMM) penicillin binding protein 7/8 (PBP 7/8) is essential in vivo (i.e., required for bacterial survival in a host) in rat pneumonia and subcutaneous abscess infection models, and is required for survival in human serum and ascites. Our initial studies on PBP 7/8 were performed in an antimicrobial sensitive strain AB307-0294. These findings have since been confirmed with the extensively drug resistant (XDR) strain HUMC1. Since our initial observation other investigators, using INseq and Tn-seq, have shown that PBP 7/8 is needed for A. baumannii survival in the Galleria mellonella insect infection model and serum respectively. PBP 7/8 has many characteristics that support its potential as a high value drug target. However, based on studies in rich laboratory medium, LMM PBPs including PBP 7/8 have been perceived to be non-essential. As a result, PBP 7/8 have received scant attention as an antibacterial target and has not been considered for A. baumannii. However, our data contradicts this paradigm and endorses the need for additional studies on PBP 7/8 in XDR A. baumannii. Therefore, our objective is to validate PBP 7/8 as a drug target, delineate mechanisms that mediate its ex vivo and in vivo essentiality, and to identify compounds that inactivate PBP 7/8. Objectives and Methods. To achieve these objectives, studies on PBP 7/8 will be extended to include additional XDR strains of A. baumannii to confirm our findings are generalizable (aim 1). Aim 1 also will also explore mechanisms by which PBP 7/8 enables growth/survival of A. baumannii ex vivo and in vivo and identify the innate host defense factors it protects against. Increasing data support the need to treat infections due to XDR isolates with multiple agents, thereby increasing efficacy and protecting against the development of resistance. Our demonstration that the loss of PBP 7/8 production increases susceptibility to complement and lysozyme mediated bactericidal activity and changes cell structure supports the hypothesis that the inability to produce PBP 7/8 affects permeability, a critical factor in the intrinsic antimicrobial resistance of A. baumannii. Therefore, an additional goal of this proposal will be to assess the whether the loss of PBP 7/8 production enhances the activity of adjunctive therapy with antimicrobials and/or monoclonal antibodies directed against the capsule (aim 2). Additional studies in aim 2 will assess whether the loss of PBP 7/8 affects the production of other PBPs and ampC expression. These data will generate additional mechanistic insights into the consequences of not being able to produce PBP 7/8. Lastly, aim 3 will begin the process of identifying a “tool” compound that is active against PBP 7/8. A live wild-type XDR strain will be screened against a chemical library to identify compounds directed against PBP 7/8 that possess bactericidal activity. Additional orthogonal assays will establish specificity, determine their quality, and prioritize identified inhibitors for downstream optimization and pre-clinical studies. Deliverables from this proposal will validate the paradigm shift on the value of PBP 7/8 as an antimicrobial target and open an untapped venue for the development of a new class of antimicrobial agents against this XDR pathogen.

对退伍军人医疗保健的预期影响。高耐药性药物导致的感染发生率 鲍曼不动杆菌在增加。已经报道了真正的泛耐药（PDR）菌株。 不幸的是，新批准的抗菌药物头孢洛扎-他唑巴坦、头孢他啶-阿维巴坦和 美罗培南/瓦硼巴坦对耐药A.鲍曼不动杆菌。需要确定新的 抗A.鲍曼尼正在施压。 背景我们证明了A.鲍曼不动杆菌低分子量青霉素结合 蛋白质7/8（PBP 7/8）在体内是必需的（即，细菌在宿主中存活所需）， 皮下脓肿感染模型，并且是在人血清和腹水中存活所必需的。我们最初 在抗微生物敏感菌株AB 307 -0294中进行了对PBP 7/8的研究。这些发现 广泛耐药（XDR）菌株HUMC 1。从我们最初的观察 使用INseq和Tn-seq的其他研究者已经表明，A.鲍曼不动杆菌存活率 大蜡螟昆虫感染模型和血清。PBP 7/8具有许多特性， 支持其作为高价值药物靶点的潜力。然而，基于丰富的实验室培养基中的研究，LMM 包括PBP 7/8在内的PBP被认为是非必需的。因此，PBP 7/8收到的很少 注意作为抗菌靶标，并且尚未考虑用于A.鲍曼不动杆菌。然而，我们的数据 与这种范式相矛盾，并支持对XDR A中PBP 7/8进行额外研究的必要性。鲍曼不动杆菌。 因此，我们的目标是验证PBP 7/8作为药物靶点，阐明介导其表达的机制， 体内和体内的必要性，并确定化合物的PBP 7/8。 目标和方法。为达致这些目的，我们会把“警察局警诫计划7/8”的研究范围扩大， 另外的A. baumannii，以证实我们的研究结果是可推广的（目标1）。Aim 1还将 探索PBP 7/8使A.体外和体内鲍曼不动杆菌， 找出它所防御的宿主固有防御因子。越来越多的数据支持治疗感染的必要性 由于XDR分离株具有多种药物，从而提高了疗效并防止了 抗战我们证明，PBP 7/8生产的损失增加了对补体的敏感性， 和溶菌酶介导的杀菌活性和改变细胞结构支持了这一假设， 不能产生PBP 7/8影响渗透性，这是A. 鲍曼不动杆菌。因此，本提案的另一个目标是评估PBP 7/8的丢失是否 生产增强了抗微生物剂和/或单克隆抗体的连续治疗的活性 瞄准胶囊（目标2）。目标2中的其他研究将评估PBP 7/8的缺失是否影响 其他PBP的产生和ampC的表达。这些数据将产生额外的机械见解 无法生产PBP 7/8的后果。最后，目标3将开始确定 一种对PBP 7/8有活性的“工具”化合物。活的野生型XDR菌株将针对以下菌株进行筛选： 化学文库，以鉴定具有杀菌活性的针对PBP 7/8的化合物。额外 正交试验将建立特异性，确定其质量，并优先考虑已鉴定的抑制剂， 下游优化和临床前研究。本提案的可验证性将验证该范例 转变PBP 7/8作为抗菌靶标的价值，并为开发 针对这种XDR病原体的一类新的抗微生物剂。