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

对退伍军人医疗保健的预期影响。由高度耐药引起的感染发生率 鲍曼不动杆菌正在增加。已经报道了真正的PAN耐药(PDR)菌株。 不幸的是，新批准的抗菌药头孢洛氮烷-他唑巴坦、头孢他啶-阿维巴坦和 美罗培南/沃博巴坦对耐药鲍曼不动杆菌活性较差。需要确定新的 抗鲍曼不动杆菌的抗菌药迫在眉睫。 背景资料。我们已经证明鲍曼不动杆菌与低分子质量(LMM)青霉素结合 蛋白7/8(PBP 7/8)在大鼠肺炎和肺炎中是体内必需的(即细菌在宿主中生存所必需的)。 皮下脓肿感染模型，是在人血清和腹水中生存所必需的。我们最初的 PBP 7/8的研究是在一株抗生素敏感菌株AB307-0294中进行的。这些发现有 自确认与广泛耐药(XDR)株HUMC1。从我们最初的观察开始 其他研究人员使用INSEQ和TN-SEQ表明，鲍曼不动杆菌存活需要ppp 7/8。 分别建立梅隆格氏杆菌昆虫感染模型和血清。PBP7/8具有许多特征， 支持其作为高价值药物靶标的潜力。然而，基于对丰富的实验室介质的研究，LMM 包括PBP 7/8在内的PBP一直被认为是不必要的。因此，PBP 7/8收到的资金很少 注意作为抗菌靶标，还没有考虑用于鲍曼不动杆菌。然而，我们的数据 与这一范例相矛盾，并赞同有必要对鲍曼氏XDR的PBP 7/8进行进一步研究。 因此，我们的目标是验证PBP7/8作为药物靶点，描述其介导其 体内和体内的重要性，并确定使PBP 7/8失活的化合物。 目标和方法。为了实现这些目标，关于方案预算草案7/8的研究将扩大到包括 鲍曼不动杆菌的其他XDR菌株证实了我们的发现是可推广的(目标1)。Aim 1也将 探讨PBP 7/8促进鲍曼不动杆菌体内外生长/存活的机制 确定它所保护的固有宿主防御因素。越来越多的数据支持治疗感染的需要 由于XDR与多种药物分离，从而提高了疗效并防止了疾病的发展 抵抗的力量。我们的证据表明，PBP7/8产量的损失增加了补体的易感性 和溶菌酶介导的杀菌活性和改变细胞结构支持这一假说 不能产生PBP7/8会影响渗透性，而渗透性是A。 鲍曼尼。因此，这项提案的另一个目标将是评估7/8 ppb的损失是否 生产可增强抗微生物和/或单抗辅助治疗的活性 瞄准胶囊(目标2)。AIM 2的其他研究将评估PBP 7/8的损失是否会影响 其他PBPs的产生和AmpC的表达。这些数据将产生更多机械性的见解 无法生产7/8方案的后果。最后，目标3将开始确定 一种对PBP7/8有活性的“工具”化合物。一种活的野生型XDR菌株将被筛选出来对抗 化学文库，以鉴定针对PBP7/8的具有杀菌活性的化合物。其他内容 正交分析将确定特异性，确定它们的质量，并对已识别的抑制剂进行优先排序 下游优化和临床前研究。此提案的可交付成果将验证该范例 转移PBP 7/8作为抗菌目标的价值，并为开发 针对这种XDR病原体的一类新的抗菌剂。

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.