Mechanisms of antibiotic reistance in confined microcolonies

描述(申请人提供)：细菌是群居时表现出不同表型的社会有机体，这种变化通常会导致毒力增强。对种群数量增加的表型反应包括形成耐抗生素的固着生物膜群落，对可扩散信号的基因表达模式的修改(群体感应)，以及群体运动(蜂群)。我们对细菌社会反应的理解主要来自对培养瓶和培养板中细菌的体外研究，这些细菌群落通常包含超过108个细胞。虽然大量种群的行为在某些环境中可能很重要，但自然界中的细菌通常居住在个体数量少得多的致密微簇中；重要的是，已提出这些簇是许多病原体的主要传播途径，包括铜绿假单胞菌、金黄色葡萄球菌和霍乱弧菌。尽管迫切需要了解细菌微簇中社会表型的开始和维持，但由于缺乏将细菌组织成3D模式的技术，这些群体中的群体行为的基本要求仍然在很大程度上是未知的，这些模式包含密度可调的特定数量的细胞。在这项提议中，我们描述了利用基于三维(3D)蛋白质的微制造来在某些情况下动态控制小细菌种群的空间排列的策略，这项技术将被用来阐明细菌微簇中依赖于种群的抗生素耐药性的基础。这项R21拨款的研究重点是临床上重要的革兰氏阴性杆菌铜绿假单胞菌，它是囊性纤维化死亡的主要原因，并将在未来的研究中扩展到其他病原体，包括金黄色葡萄球菌。 与公共卫生相关：许多感染是由较小的细菌聚集群引起的。从公共卫生的角度来看，这些聚集的人口显示出重要的特征，包括对抗菌素的抗药性和高传染性。这项研究计划的目标是了解这些特征的分子基础，最终目标是设计新的治疗策略来治疗它们。。

DESCRIPTION (provided by applicant): Bacteria are social organisms that display distinct phenotypes when present in groups, changes that often result in heightened virulence. Phenotypic responses to increased population size include formation of antibiotic-resistant sessile biofilm communities, modification of gene expression patterns in response to diffusible signals (quorum sensing), and group motility (swarming). Our understanding of bacterial social responses derives primarily from in vitro studies of bacteria in flasks and on culture plates, communities that often contain greater than 108 cells. Although the behavior of very large populations may be important in some environments, bacteria in nature often reside in dense micro-clusters having far fewer individuals; importantly, it has been proposed that these clusters are the primary means of transmission of many pathogens, including Pseudomonas aeruginosa, Staphylococcus aureus, and Vibrio cholerae. Despite the strong imperative to understand onset and maintenance of social phenotypes within bacterial micro-clusters, fundamental requirements for group behaviors in these populations remain largely unknown due to a dearth of technologies for organizing bacteria into 3D patterns that contain specified numbers of cells at tunable densities. In this proposal, we describe strategies for exploiting three-dimensional (3D) protein-based microfabrication to control, in some cases, dynamically, spatial arrangements of small bacterial populations, technology that will be used to elucidate the basis for population-dependent antibiotic resistance in bacterial micro-clusters. The studies in this R21 grant focus on the clinically important, Gram-negative bacterium P. aeruginosa, a primary cause of cystic fibrosis mortality, and will be extended in future studies to other pathogens, including S. aureus. PUBLIC HEALTH RELEVANCE: Many infections are caused by small aggregate populations of bacteria. These aggregate populations display important traits from a public health standpoint, including resistance to antimicrobials and high infectivity. The goal of this research proposal is to understand the molecular basis for these traits with the ultimate goal of devising new therapeutic strategies for treating them. .