Gene expression in S aureus biofilms

描述（由申请人提供）：该项目的长期目标是表征葡萄球菌生物膜的特性，这些特性解释了葡萄球菌对抗菌化疗的耐药性。金黄色葡萄球菌是生物膜相关感染的重要原因，如原生瓣膜心内膜炎、骨髓炎和医疗器械相关感染。涉及葡萄球菌生物膜的感染通常很难用抗生素治疗，并且可能复发。生物膜的特点，使其难以抗生素治疗，目前还不清楚。在本研究中，基因调控或“转录适应”在生物膜对抗生素的抗性中的作用将被分析。一种未经证实的可能性是，生物膜比浮游细胞对抗生素的抵抗力更强，因为它们具有“超适应性”，或者通过快速激活与压力相关的基因来对压力环境条件做出反应。另一种假设是，由于胞外多糖基质的扩散限制，生物膜内的细胞比浮游细胞有更多的时间在转录水平上对抗生素作出反应。这两种假设都挑战了一种普遍的观念，即使生物膜对抗生素产生耐药性的特性是构成性的，而不是在抗生素暴露后诱导的。为了验证这些假设，将通过微阵列分析对浮游细胞和生物膜中对三种不同种类的抗生素作出反应而激活的基因进行全球筛选。在对抗生素治疗的反应中被显著诱导或抑制的基因将进一步以诱变为特征。希望更好地了解生物膜的抗生素耐药性机制将推动用于对抗这些感染的治疗方法的发展，并期望这些研究将增加我们目前对应激反应调节的了解。

DESCRIPTION (provided by applicant): The long-term objective of this project is to characterize the properties of staphylococcal biofilms that account for their resistance to antimicrobial chemotherapy. S. aureus is an important cause of biofilm-related infections such as native valve endocarditis, osteomyelitis, and medical device-related infections. Infections involving staphylococcal biofilms are often very difficult to treat with antibiotics and may be recurrent. The characteristics of biofilms that make them refractory to antibiotic therapy are not well understood at this time. In this study the role of gene regulation or "transcriptional adaptation" in the resistance of biofilms to antibiotics will be analyzed. One untested possibility is that biofilms are more resistant to antibiotics than planktonic cells because they are "hyper-adaptable" or uniquely poised to respond to stressful environmental conditions through the rapid transcriptional activation of stress-related genes. An alternative hypothesis is that cells within a biofilm have more time to respond at the transcriptional level to antibiotics than do their planktonic counterparts due to diffusion limitations imparted by the exopolysaccharide matrix. Both of these hypotheses challenge the common notion that the properties that make biofilms resistant to antibiotics are constitutive rather than induced following antibiotic exposure. In order to test these hypotheses, a global screen of genes activated in planktonic cells and biofilms in response to antibiotics from three distinct classes will be conducted by microarray analysis. Genes that are significantly induced or repressed in response to antibiotic treatment will be further characterized by mutagenesis. It is hoped that a better understanding of the mechanism of antibiotic resistance of biofilms will advance the development of therapies used to combat these infections and it is expected that these studies will increase our current knowledge of the regulation of the stress response.