The Impact of Vancomycin-Resistant Entercoccus on Clostridium difficile Infection

项目摘要 艰难梭菌是美国最常见的医院病原体， 全球公共卫生威胁。在过去的十年中，与C。艰难 感染（CDI）急剧增加;然而，控制这种广谱疾病的因素 仍然不清楚。CDI的主要危险因素是抗生素的使用，这降低了对C. 通过改变肠道微生物菌群来解决问题。有趣的是，主要的医院病原体万古霉素- 耐药肠球菌（VRE）与C.这些病原体通常 一起出现在胃肠道中此外，VRE定植与更严重的C。 在艰难梭菌相关疾病和患者亚群中，CDI增加了VRE引起菌血症的风险。 尽管有这些强烈的关联，但很少有工作去探索它们之间的分子相互作用。 肠球菌和C.在感染过程中，这些病原体很难分离，目前还不清楚这些病原体的共同出现有什么影响 对秀丽隐艰难梭相关疾病物种间的相互作用可以归因于许多 多种微生物感染，包括CDI，细菌之间的串扰与急性 几种疾病。肠球菌与对CDI的易感性增加和肠道微生物群相关， CDI患者肠球菌高度富集。补充过量锌后， 肠球菌在微生物群中高度富集，这导致对CDI的易感性增加， 梭艰难梭菌相关疾病和高水平的肠球菌易位到肝脏。初步数据 表明在培养中，肠球菌和C.艰难梭菌直接相互作用，这种串扰改变了毒力， 这两种病原体的行为。在本申请中，我们建议阐明 肠球菌属和C.并定义这些相互作用对易感性和严重性的影响。 CDI.我们假设：（i）肠球菌通过改变肠道景观增加对CDI的易感性 提高C.艰难梭菌定植和（ii）肠球菌和C.胃肠道艰难梭菌 道促进了这两种重要病原体之间的相互作用，从而增加了持久性并加剧了 疾病期间CDI。我们计划通过一系列综合的具体目标来检验这三个假设。第一、 我们将剖析肠球菌丰度和对C.梭茵和 确定肠球菌对C.艰难梭菌在小鼠中的毒力（目的1）。然后我们将定义如何 这些病原体在感染过程中相互作用，并检查细菌相互作用对疾病的影响（目的2）。 这些实验将阐明VRE对CDI易感性、严重性和复发的影响， 大大增加了我们对C.艰难梭菌与其他常见致病菌相互作用 在感染期间。通过完成这一建议所获得的见解将为小说奠定基础。 旨在破坏促进C.艰难感染

PROJECT SUMMARY Clostridium difficile is the most commonly reported nosocomial pathogen in the United States and an urgent public health threat worldwide. Over the past decade, incidence, severity, and costs associated with C. difficile infection (CDI) have increased dramatically; however, the factors that govern this broad spectrum of disease remain unclear. The primary risk factor for CDI is antibiotic use, which reduces colonization resistance to C. difficile by altering the resident gut microbiota. Interestingly, the major nosocomial pathogen vancomycin- resistant Enterococcus (VRE) shares numerous risk factors with C. difficile and these pathogens are commonly found together in the gastrointestinal tract. Moreover, colonization with VRE is associated with more severe C. difficile-associated disease and in subsets of patients, CDI increases the risk of bacteremia due to VRE. Despite these strong associations, little work has been done to explore the molecular interactions between Enteroccoci and C. difficile during infection and it is unclear what impact co-occurrence of these pathogens has on C. difficile-associated disease. Interspecies interactions can be attributed to the development of numerous polymicrobial infections, including CDI, and cross talk between bacteria is associated with exacerbation of several diseases. Enterococcus is associated with increased susceptibility to CDI and the gut microbiota of patients with CDI is highly enriched with Enterococci. Following excess Zn supplementation, commensal Enterococci are highly enriched in the microbiota, which leads to increased susceptibility to CDI, exacerbation of C. difficile-associated disease, and high levels of Enterococcus translocation to the liver. Preliminary data suggests that in culture, Enterococcus and C. difficile directly interact and this cross-talk alters virulence and behavior of these two pathogens. In this application, we propose to elucidate the interactions between Enterococcus and C. difficile and define the impact that these interactions have on susceptibility and severity of CDI. We hypothesize that (i) Enterococcus increases susceptibility to CDI by altering the landscape of the gut to enhance C. difficile colonization and (ii) co-occurrence of Enterococcus and C. difficile in the gastrointestinal tract facilitates cross-talk between these two important pathogens that increases persistence and exacerbates disease during CDI. We plan to test these three hypotheses through a series of integrated Specific Aims. First, we will dissect the relationship between Enterococcus abundance and susceptibility to C. difficile and determine the contribution of Enterococcus to C. difficile virulence in mice (Aim 1). We will then define how these pathogens interact during infection and examine the impact of bacterial cross-talk on disease (Aim 2). These experiments will elucidate the impact of VRE on susceptibility, severity, and recurrence of CDI and will substantially increase our understanding of how C. difficile interacts with other common pathogenic microbiota during infection. The insights gained by completion of this proposal will lay the foundation for novel therapeutics that aim to disrupt the molecular interactions that facilitate C. difficile infection.