Biofilms and Enterococcus faecalis Biology

描述（由申请方提供）：粪肠球菌i是从受损患者的医院相关感染中最常分离的三种菌种之一，可引起高度致命性心内膜炎。肠球菌的医学重要性因其对抗菌剂的高度固有和获得性耐药性以及其倾向于充当将耐药基因传播到更高致病性生物体的主要管道而增强。肠球菌通常从植入的医疗器械上形成的生物膜中分离出来，在心脏瓣膜上的定植和生长也被认为是生物膜生长的一种形式。生物膜环境可能是肠球菌对万古霉素高水平耐药性转移到金黄色葡萄球菌的一个小生境。我们已经使用遗传筛选来识别大量的新的体外生物膜形成的遗传决定因素，并且正在进行的研究提供了越来越多的证据，证明许多这些决定因素在体内感染期间形成的生物膜中的重要性。许多先前未表征的肠球菌生物膜决定簇在多种重要病原体中显示出显著的保守性;如果它们在功能上保守，则这些基因的产物构成了用于开发化学抑制剂或疫苗的潜在靶点库，所述化学抑制剂或疫苗可以在由许多不同病原体产生的感染期间阻断生物膜形成。目前资助的结果为回答有关肠球菌生物膜形成生物学的重要基本问题提供了坚实的基础，以及增加我们对细菌致病机制的理解的新方法。为解决这些问题提出的具体目标是：1.利用本基金提供的信息和资源来确定关键信号和调控机制，这些信号和调控机制涉及：a）从生物膜生长到生物膜生长的初始过渡，以及B）生物膜群落的后续发展。2.确定肠球菌生物膜形成相关基因的破坏对毒力的影响，并鉴定S.金黄色葡萄球菌中发现的新的生物膜决定簇池。粪便3.确定大肠杆菌核心基因组中生物膜诱导的抗生素抗性的决定因素。粪便 公共卫生相关性：这项申请中提出的研究集中在一种名为粪肠球菌的细菌能够在称为生物膜的结构中在表面上生长的过程。近年来，已经广泛接受的是，生物膜中的细菌生长导致细菌的生理学和行为与液体培养物中观察到的细菌的生理学和行为的主要差异，并且生物膜形成涉及许多（如果不是大多数）细菌感染的产生。我们的研究将采用遗传技术来识别和表征以前未研究的在生物膜形成中重要的肠球菌基因，并确定另一种重要病原体金黄色葡萄球菌中的类似基因是否具有与肠球菌基因相同的生物学功能。如果这些基因具有功能保守性，就可以加速新的抗菌药物或疫苗的开发。

DESCRIPTION (provided by applicant): Enterococcus faecalis iis one of the top three most frequently-isolated species from hospital- associated infections of compromised patients and it can cause a highly fatal form of endocarditis. The medical importance of the enterococci is enhanced by their high degree of inherent and acquired resistance to antimicrobial agents, and by their propensity to act as a major conduit for the spread of resistance genes to more highly-pathogenic organisms. Enterococci are commonly isolated from biofilms formed on implanted medical devices, and colonization and growth on heart valves is also considered a form of biofilm growth. The biofilm environment is a likely niche for transfer of high-level vancomycin resistance from enterococci to Staphylococcus aureus. We have used genetic screens to identify a large number of novel genetic determinants of biofilm formation in vitro, and ongoing studies provide increasing evidence for the importance of many of these determinants in biofilms formed in vivo during infections. Many previously un-characterized enterococcal biofim determinants show significant conservation in a variety of important pathogens; if they are functionally conserved, the products of these genes comprise a pool of potential targets for the development of chemical inhibitors or vaccines that could block biofilm formation during infections produced by many different pathogens . The results from the current grant provide a strong foundation for answering important basic questions about the biology of enterococcal biofilm formation, as well as new approaches to increasing our understanding of bacterial pathogenic mechanisms. The specific aims proposed to address these questions are to: 1. Use the information and resources from the present grant to identify critical signals and regulatory mechanisms involved in: a) the initial transition from planktonic to biofilm growth and, b) the subsequent development of the biofilm community. 2. Determine the effects of disruption of genes involved in enterococcal biofilm formation on virulence and identify functionally-conserved biofilm/virulence genes in S. aureus from the pool of novel biofilm determinants discovered in E. faecalis. 3. Identify determinants of biofilm-induced antibiotic resistance in the core genome of E. faecalis. PUBLIC HEALTH RELEVANCE: The research proposed in this application is focused on the process by which a bacterium called Enterococcus faecalis is able to grow on surfaces in a structure called a biofilm. In recent years it has become widely accepted that bacterial growth in biofilms causes major differences in the physiology and behavior of bacteria from that observed in liquid cultures, and that biofilm formation is involved in the production of many, if not most bacterial infections. Our research will employing genetic techniques to identify and characterize previously un-studied enterococcal genes that are important in biofilm formation, and to determine whether similar genes in another important pathogen, Staphylococcus aureus, have the same biological functions as the enterococcal genes. If there is functional conservation of these genes, it could speed the development of new antimicrobial drugs or vaccines.