Mechanistic basis of bacteriophages for the decolonization of vancomycin resistant enterococci in the intestine.

项目摘要/摘要 多重耐药(MDR)细菌感染的发生率正在上升。这一点与Gram尤其相关- 条件致病菌和医院主要病原菌--粪肠球菌 菌血症。耐多药粪肠球菌感染的增加在很大程度上归因于他们对多种抗生素的抵抗能力。 包括“最后手段”的抗生素，如万古霉素。粪肠球菌是人类肠道的原生居民。 作为粪肠多药耐药菌主要储藏者的区域。肠道微生物区系的抗生素耗竭可能 促进粪肠球菌的大量繁殖，使其更好地扩散到血液和其他组织部位。 在许多情况下，肠球菌的过度生长是由万古霉素耐药肠球菌(VRE)主导的。 这严重限制了可用的治疗选择。随着全球VRE感染的增加，当务之急是 探索了治疗干预的新策略。传统抗生素的另一种替代方法是使用 用于治疗抗药性细菌感染的生物制剂。一种方法是利用 感染和杀死细菌的噬菌体。尽管噬菌体有望成为下一代 治疗学方面，我们对体内噬菌体感染过程的基本原理以及哺乳动物如何 宿主环境影响噬菌体与细菌的相互作用。这个项目调查了噬菌体对 VRE在其自然肠道栖息地内的非殖民化。结合使用小鼠肠道定植 模型、分子遗传学和全基因组测序，我们的目标是从机制上深入了解 噬菌体介导的肠道选择压力影响噬菌体的感染性和基因组进化 VRE非殖民化。为了实现这一目标，我们将执行三个具体目标：1)定义肠道选择性 决定噬菌体介导的粪肠球菌非殖民化的压力，2)决定长期稳定性和 粪肠球菌噬菌体的基因组进化，以及3)确定不同来源的同源受体 粪肠球菌噬菌体和描述受体的功能。了解肠道选择性压力和 体内感染肠球菌噬菌体的分子机制将有助于新型噬菌体的开发 对常规抗生素不耐药的肠球菌非殖民化治疗。

Project Summary/Abstract The incidence of multidrug resistant (MDR) bacterial infections is rising. This is particularly relevant for the Gram- positive bacterium Enterococcus faecalis, an opportunistic pathogen and leading cause of nosocomial bacteremia. The rise in MDR E. faecalis infections is largely attributed to their ability to resist many antibiotics including antibiotics of “last resort”, such as vancomycin. E. faecalis is a native inhabitant of the human intestinal tract which serves as a major reservoir of MDR E. faecalis. Antibiotic depletion of the intestinal microbiota can facilitate blooms of E. faecalis leading to their enhanced dissemination to the bloodstream and other tissue sites. In many cases overgrowth of intestinal enterococci is dominated by vancomycin resistant enterococci (VRE) which severely limits available treatment options. With increasing VRE infections worldwide, it is imperative that new strategies for therapeutic intervention are explored. An alternative to traditional antibiotics is the use of biological agents for the treatment of drug resistant bacterial infections. One approach is harnessing bacteriophages (phages) that infect and kill bacteria. Although phages may hold promise as next generation therapeutics, we know little of the basic principles of phage infection processes in vivo and how the mammalian host environment influences phage-bacteria interactions. This project investigates the use of phages for the decolonization of VRE within its natural intestinal habitat. Using a combination of mouse intestinal colonization models, molecular genetics and whole genome sequencing, we aim to gain mechanistic insight into how intestinal selective pressures influence the infectivity and genome evolution of phages during phage-mediated VRE decolonization. To achieve this goal we will execute three specific aims: 1) Define the intestinal selective pressures that dictate phage-mediated E. faecalis decolonization, 2) Determine the long-term stability and genomic evolution of E. faecalis phages in the intestine, and 3) Determine cognate receptors for diverse E. faecalis phages and delineate receptor function. Understanding intestinal selective pressures and molecular mechanisms of enterococcal phage infection in vivo will aid in the development of novel phage therapeutics for the decolonization of enterococci recalcitrant to conventional antibiotics.