Biofilm Dissemination in Staphylococcus aureus

描述（由申请方提供）：金黄色葡萄球菌是一种多功能病原体，可引起多种感染。除了其庞大的毒力因子库，S。Aures可以在对抗生素治疗和宿主防御无效的生物膜群落中生长。它 估计80%的S.金黄色葡萄球菌医院感染与生物膜有关。葡萄球菌生长和感染的这一重要方面受到越来越多的关注，但我们仍然没有完全了解其背后的分子机制。生物膜的发展通常可以分为四个阶段：粘附，积累，成熟和分散。成熟的葡萄球菌生物膜的特征在于包裹在复杂结构中的细菌群落，所述复杂结构由胞外聚合物物质组成，所述胞外聚合物物质包括从活性细胞死亡释放的细胞外DNA（eDNA）。生物膜群落在代谢上是异质的，并且每个细胞的生理状态由其在不同环境小生境（例如需氧、厌氧）内的位置决定。细胞也从生物膜中主动释放，这使得感染传播到宿主的其他区域。以前我们已经描述了一个新的基因msa，它参与了毒力和生物膜发育的调控。在本申请中， 我们将检验这样的假设，即通过在体外和体内调节结构和分散因子，MSA在生物膜成熟和/或分散中起关键作用。我们还假设msa突变引起的生物膜结构缺陷将导致生物膜相关感染中病原体影响的降低和宿主清除率的增加。最后，由于本研究的最终目标是利用msa作为治疗靶点来增强常规治疗，我们将在体内研究msa对生物膜对抗生素治疗敏感性的影响。我们已经开发了两个具体的目标来测试这一假设：1）定义在生物膜发展中的三个代表性的临床分离株的msa的作用。我们将使用共聚焦显微镜和蛋白质组学研究生物膜的成熟和分散阶段。我们还将绘制出生物膜内msa的表达。2)用小鼠模型确定msa在生物膜相关感染、宿主反应和抗生素敏感性中的作用。这项研究的发现将导致抗生物膜疗法的发展，这对对抗寄生虫感染至关重要。

DESCRIPTION (provided by applicant): Staphylococcus aureus is a versatile pathogen that causes a wide variety of infections. In addition to its large arsenal of virulence factors, S. aures can grow in biofilm communities that are recalcitrant to antibiotic treatment and host defenses. It is estimated that 80% of S. aureus hospital infections are associated with biofilm. This important aspect of staphylococcal growth and infection has received increased attention, yet we still do not fully understand the molecular mechanisms behind it. Biofilm development can generally be divided into four stages: adherence, accumulation, maturation and dispersion. Mature staphylococcal biofilms are characterized as bacterial communities encased in complex structures comprised of extrapolymeric substances that include extracellular DNA (eDNA) released from active cell death. Biofilm communities are metabolically heterogeneous and the physiological state of each cell is dictated by its location within the different environmental niches (e.g. aerobic, anaerobic). Cells are also actively released from the biofilm, which allows the infection to disseminate to other areas in the host. Previously we have characterized a new gene, msa that is involved in regulation of virulence and biofilm development. In this application, we will test the hypothesis that msa plays a key role in biofilm maturation and/or dispersion by regulating structuring and dispersion factors both in vitro and in vivo. We also hypothesize that the structural defects in biofilm caused by mutation of msa will lead to reduced pathogenic impact in biofilm-associated infections and increased clearance by the host. Finally, since the ultimate goal of this study is to exploit msa as a therapeutic target to enhance conventional therapy, we will examine the impact of msa on biofilm susceptibility to antibiotic treatment in vivo. We have developed two specific aims to test this hypothesis: 1) Define the role of msa in biofilm development in three representative clinical isolates. We will examine the maturation and dispersion stages of biofilm using confocal microscopy and proteomics. We will also map out the expression of msa within biofilm. 2) Define the role of msa in biofilm-associated infections, host responses and susceptibility to antibiotics using a murine model. Findings from this study will lead to development of anti-biofilm therapies that will be critical to combat recalcitrant infections.