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

项目总结 噬菌体(噬菌体)作为抗菌治疗药物正在获得吸引力，这主要归功于几个备受瞩目的 用作紧急批准的实验生物制品。噬菌体疗法的一个明显问题是 细菌噬菌体耐药性的发展将限制噬菌体作为临床相关治疗方法的使用。这 结论忽略了噬菌体抗药性发展过程中的一个根本缺陷，即细菌经常引起 由于获得性噬菌体抵抗力而降低适合度。这些健康权衡包括增强的抗生素 易感性，降低的毒性，以及无法稳定地定植它们的宿主。这篇文章中描述的工作 提案将利用噬菌体耐药性的出现作为一种成功治疗顽固性疾病的手段 寄居在肠道中的机会性病原体。我们将使用革兰氏阳性肠道共生菌和 条件致病菌粪肠球菌和粪肠球菌作为模式菌检测 噬菌体抗性表型如何影响其在肠道中的适合性，以及这些结果是否会 作为新的治疗方法加以利用。具体地说，我们将定义驱动噬菌体的机制 粪肠球菌和粪肠球菌通过执行三个特定目标而产生的抵抗力适应性缺陷：1) 噬菌体耐药株携带细胞肠道定植缺陷的机制研究(S) 表面胞外多糖突变；2)研究噬菌体介导的肽聚糖突变 水解酶基因SAGA导致抗生素敏感性；以及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.