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

项目摘要 噬菌体（Bacteriophages，简称BPHs）作为抗菌治疗剂正在获得牵引力，这主要是由于几种备受瞩目的 用作紧急批准的实验生物制剂。噬菌体疗法的一个公认的问题是， 细菌噬菌体耐药性的发展将减少使用作为临床相关疗法的抗生素。这 结论忽略了噬菌体耐药性发展的一个根本缺陷，即细菌常常引起 由于获得性噬菌体抗性而降低的适应性。这些健身权衡包括增强抗生素 易感性，降低的毒力，以及不能稳定地定殖其宿主。本文所描述的工作 一项提案将利用噬菌体耐药性的出现，作为成功治疗疟疾的一种手段 寄生在肠道内的机会致病菌。我们将使用革兰氏阳性肠道菌， 条件致病菌粪肠球菌和屎肠球菌作为模式生物，以确定 噬菌体抗性表型如何影响它们在肠道中的适应性，以及这些结果是否可以 作为新的治疗方法。具体来说，我们将定义驱动噬菌体的机制， 抗性适合度缺陷型E. faecalis和E.肠道内的粪便通过执行三个特定的目标：1） 确定驱动携带细胞的噬菌体抗性菌株的肠定殖缺陷的机制， 表面外泌多糖突变; 2）检查噬菌体介导的肽聚糖突变如何 水解酶基因佐贺导致抗生素敏感性;和3）确定噬菌体-抗生素组合是否降低 肠球菌肠道定植。

PROJECT SUMMARY Bacteriophages (phages) are gaining traction as antibacterial therapeutics largely due to several high profile uses as emergency-approved experimental biologics. A perceived problem with phage therapy is that the development of bacterial phage resistance will curtail the use of phages as clinically relevant therapies. This conclusion overlooks a fundamental flaw in the development of phage resistance, that is, bacteria often incur reduced fitness as a result of acquired phage resistance. These fitness tradeoffs include enhanced antibiotic susceptibility, reduced virulence, and the inability to stably colonize their host. The work described in this proposal will capitalize on the emergence of phage resistance as a means to successfully treat recalcitrant opportunistic pathogens that reside in the intestine. We will use the Gram-positive intestinal commensals and opportunistic pathogens Enterococcus faecalis and Enterococcus faecium as model organisms to determine how phage resistance phenotypes influence their fitness in the intestine and whether these outcomes can be leveraged as novel therapeutic approaches. Specifically, we will define the mechanisms that drive phage resistance fitness defects of E. faecalis and E. faecium within the intestine by executing three specific aims: 1) to define the mechanism(s) driving the intestinal colonization deficiency of phage resistant strains harboring cell surface exopolysaccharide mutations; 2) to examine how phage-mediated mutations in the peptidoglycan hydrolase gene sagA result in antibiotic sensitivity; and 3) to determine if phage-antibiotic combinations reduce enterococcal intestinal colonization.