Carbapenemase-Stable Carbapenem Antibiotics for Treatment of Multidrug-Resistant Acinetobacter baumannii Infections

鲍曼不动杆菌被美国疾病控制与预防中心列为对抗生素产生严重耐药性的临床病原菌。 在美国的威胁，由于其对碳青霉烯类抗生素(碳青霉烯类抗药性)的抗药性 鲍曼氏杆菌或螃蟹)，这是治疗这种微生物引起的感染的首选药物。 此外，螃蟹往往对不同类别的抗菌剂(多药耐药鲍曼不动杆菌)具有抗药性 或MDRAb)，这严重限制了可用的治疗选择。初步探讨了A. 鲍曼氏杆菌到碳青霉烯类是生产抗生素失活酶，碳青霉烯类-水解类β- 内酰胺酶或CHDLS。此外，A类和B类碳青霉烯类酶、碳青霉烯类靶标的敏感性 (细菌青霉素结合蛋白或PBPs)、抗生素对细菌细胞的渗透率和它们的 外排泵排出也会造成阻力。对碳青霉烯类抗生素的耐药性高达 在世界上一些地区，由这种细菌引起的感染的死亡率令人震惊 很高，高达50%。我们的长期目标是开发新的抗生素来治疗致命的MDRAb感染。 在过去的十年里，瓦库连科小组对临床上重要的 CHDLS，这为开发新一代能够抑制碳青霉烯类抗生素提供了指导 这些酶。与此同时，约翰·布伊纳克博士(co-Pi)的团队开发了数十种新的非典型修饰 碳青霉烯类抗生素。我们评估了这些抗生素对MDRAb的活性，并证明了 其中三个化合物具有优越的抗MDRAb活性(与商用碳青霉烯类抗生素相比)。三个都是 抑制最普遍的鲍曼不动杆菌CHDL，OXA-23，并具有不同的抑制活性谱 其他类别的CHDL和碳青霉烯类酶。其中一种化合物具有前所未有的广泛性 多种临床重要碳青霉烯酶的活性谱和抗水解性 分子类。在这项拨款申请中，我们建议对我们的小说进行详细的刻画 碳青霉烯类抗生素。我们将测定我们的化合物对鲍曼不动杆菌的活性。 主要CHDL和其他碳青霉烯酶，并揭示其能力的动力学和结构特征 抑制这些酶(目标1)。我们将研究我们的新型碳青霉烯与它们的靶标多溴联苯并苯酚的相互作用。 并确定外排泵和孔道蛋白在多大程度上影响细菌对这些抗生素的耐药性(目标2)。 我们将设计和表征数十种新型碳青霉烯类抗生素，以进一步提高其抗菌性能 通过增强它们对各种碳青霉烯酶的抑制效力，改善对多溴联苯并苯酚的亲和力来增强活性 提高渗透率和外流阻力(目标3)。我们将在体外进行我们最好的 用于评价其溶解性、稳定性和毒性的新型碳青霉烯类抗生素。最后，我们将对我们最好的化合物进行评估 在动物研究中，评价它们作为对抗MDRAb的新型治疗剂的潜力(目标4)。

Acinetobacter baumannii is listed by the CDC as a clinical pathogen that poses a serious antibiotic resistance threat in the United States, due to its resistance to the last resort carbapenem antibiotics (carbapenem-resistant A. baumannii or CRAb), which were the drugs of choice for treatment of infections caused by this microorganism. In addition, CRAb is often resistant to antimicrobial agents of different classes (multi-drug-resistant A. baumannii or MDRAb), which severely limits available therapeutic options. The major mechanism of resistance of A. baumannii to carbapenems is production of antibiotic-inactivating enzymes, carbapenem-hydrolyzing class D β- lactamases or CHDLs. In addition, carbapenemases of classes A and B, sensitivity of carbapenem targets (bacterial penicillin-binding proteins or PBPs), rates of antibiotic penetration into the bacterial cell and their expulsion by efflux pumps can also contribute to resistance. Levels of resistance to carbapenems reach up to 90% in some parts of the world, and mortality rates from infections caused by such bacteria are staggeringly high, up to 50%. Our long-term goal is to develop novel antibiotics for treatment of deadly MDRAb infections. Over the last decade, the Vakulenko group has performed in-depth characterization of clinically important CHDLs, which provides guidance for development of a new generation of carbapenems capable of inhibiting these enzymes. Concurrently, Dr. John Buynak’s (co-PI) group developed dozens of novel atypically-modified carbapenem antibiotics. We evaluated these antibiotics for their activity against MDRAb and demonstrated that three of them possess superior activity (when compared to commercial carbapenems) against MDRAb. All three inhibited the most prevalent A. baumannii CHDL, OXA-23, and had varying spectra of inhibitory activity against other CHDLs and carbapenemases of other classes. One of these compounds had an unprecedented wide spectrum of activity and resisted hydrolysis by a wide range of clinically important carbapenemases of all molecular classes. In this grant application, we propose to perform detailed characterization of our novel carbapenem antibiotics. We will determine activity of our compounds against A. baumannii strains expressing major CHDLs and other carbapenemases and unveil kinetic and structural features responsible for their ability to inhibit these enzymes (Aim 1). We will study interaction of our novel carbapenems with their targets, PBPs, and determine to what extent efflux pumps and porins influence bacterial resistance to these antibiotics (Aim 2). We will design and characterize several dozen novel carbapenem antibiotics to further improve their antimicrobial activity by enhancing their inhibitory potency against various carbapenemases, improving affinity for PBPs and increasing penetration rates and resistance to efflux (Aim 3). We will perform in vitro characterization of our best novel carbapenems to assess their solubility, stability and toxicity. Finally, our best compounds will be evaluated in animal studies to appreciate their potential as novel therapeutic agents against MDRAb (Aim 4).