Molecular Insights into the Uropathogenesis of MDR Acinetobacter baumannii

项目摘要/摘要 由鲍曼不动杆菌(Ab)引起的多药耐药(MDR)感染有 以惊人的速度增长。目前，单抗临床分离株的多药耐药频率高于其他临床分离株 革兰氏阴性菌。出于这个原因，世界卫生组织已将抗体列为 新的抗菌疗法的研究和开发。AB很大程度上与医疗保健有关- 获得性感染，即肺炎和败血症。然而，抗体引起尿路的能力 感染(UTI)，包括导管相关性UTI(CAUTI)，被低估。尽管有20%-30%的 AB分离株来源于尿路，目前还没有建立模型来研究AbUTI或其分子基础。 尿路致病抗体(UPAb)毒力。由于UPAb正在为全球MDR UTI的兴起做出贡献，因此有一个 迫切需要创造新的抗尿路感染疗法。因此，需要一种小鼠模型来研究mdr-uPAb 并确定对抗UTI起关键作用的细菌因子。我们已经开发出第一个AB导管相关的尿路感染 (CAUTI)小鼠模型检测种植体和膀胱在小鼠体内的定植情况，我们选择了MDR AB分离株ABCA1作为模式菌株。ABCA1是从阿根廷一名女性尿路感染患者身上分离出来的。品系 属于国际抗体克隆ST25，这是一个在系统发育上截然不同的紧急重要的抗体谱系 临床菌株的病理生理学研究很少。ABCA1携带一个大的MDR编码质粒， PAB5属于一类抗体大结合质粒(AbLCP)家族，在多个亚型中鉴定， 地理上不同的抗体菌株。有趣的是，我们的初步研究结果显示，pAB5授权提高了 在我们的CAUTI模型中存活，但在肺炎模型中毒力降低。与导管的粘附性和 尿路上皮是CAUTI建立的第一阶段。我们已经验证了我们的模型，显示了删除 在我们的CAUTI模型中，伴随者-引导者菌毛的存在消除了ABCA1定植导管和膀胱的能力。 同样，糖蛋白CPAA的缺失，是与T2SS相关的表达最丰富的酶之一 效应，减少ABCA1在体外人尿中的生长和在CAUTI模型中的毒力。在这 应用，我们建议利用我们在抗体分子生物学和发病机制方面公认的专业知识来 探讨卡介苗感染早期的细菌因素。我们将进一步调查这些因素 参与黏附以及参与UPAb发病机制的细胞外和表面暴露的元素。 我们还将研究pAB5如何增强ABCA1的欧洲致病状态。我们的工作揭示了AB是 不是具有停滞不前的毒力因子的同质病原体组；相反，菌株似乎 获得独特的特征，以便更好地装备它们，使它们能够在特定的宿主利基中引发疾病。创建一个Ab模型 代表这些被忽视的感染的毒株和动物疾病模型对于阻止UPAb的努力至关重要 避免加剧全球MDR UTI日益沉重的负担。我们建议的模型和调查将服务于 作为开发新的诊断和治疗方法的基础。

PROJECT SUMMARY/ABSTRACT Multidrug resistant (MDR) infections caused by the bacterial pathogen Acinetobacter baumannii (Ab) are increasing at alarming rates. Today the MDR frequencies among Ab clinical isolates are higher than any other Gram-negative bacterium. For this reason, the World Health Organization has categorized Ab as top priority for the research and development of new antimicrobial therapies. Ab is largely associated with healthcare- acquired infections, namely pneumonia and septicemia. However, the ability of Ab to cause urinary tract infections (UTI), including catheter-associated UTI (CAUTI), is underappreciated. Despite that 20-30% of the Ab isolates come from urinary sources, there is no established model to study Ab UTI or the molecular basis of uro-pathogenic Ab (UPAb) virulence. As UPAb are contributing to the rise of MDR UTI globally, there is a pressing need to create new Ab UTI therapies. Thus, there is demand for a murine model to study MDR-UPAb and to identify the bacterial factors critical for Ab UTI. We have developed the first Ab catheter-associated UTI (CAUTI) murine model to examine implant and bladder colonization in mice, and we have selected the MDR Ab isolate AbCA1 as model strain. AbCA1 was isolated from a female UTI patient in Argentina. The strain belongs to the international Ab clone ST25, a phylogenetically distinct and emergently important lineage of Ab clinical strains whose pathophysiology has been poorly studied. AbCA1 carries a large MDR-encoding plasmid, pAB5, which belongs to a family of Ab Large Conjugative Plasmids (AbLCPs) identified in multiple, geographically-diverse Ab strains. Interestingly, our preliminary findings show that pAB5 confers improved survival in our CAUTI model, but reduced virulence in a pneumonia model. Adherence to the catheter and urothelium constitutes the first stage in establishing CAUTI. We have validated our model showing that deletion of chaperone-usher pili abrogates AbCA1 ability to colonize the catheter and bladder in our CAUTI model. Similarly, deletion of the glycoprotease CpaA, one of the most abundantly expressed T2SS-associated effector, diminished AbCA1 growth in human urine in vitro and virulence in the CAUTI model. In this application, we propose to use our recognized expertise in Ab molecular biology and pathogenesis to investigate the bacterial factors involved in the early stages of Ab CAUTI. We will further investigate the factors involved in adherence and the extracellular and surface-exposed elements involved in UPAb pathogenesis. We will also investigate how pAB5 enhances the uro-pathogenic state of AbCA1. Our work reveals that Ab is not a homogenous group of pathogens with a stagnant battery of virulence factors; instead, strains appear to acquire unique traits that better equip them to cause disease in specific host niches. Establishing a model Ab strain and an animal disease model that represents these neglected infections is critical to efforts to stop UPAb from contributing to the growing global burden of MDR UTI. Our proposed models and investigations will serve as foundation for the development of novel diagnostics and therapeutics.