Development of Anti-Biofilm Agents that Target Staphylococcal Biofilms

项目总结(见说明)： 金黄色葡萄球菌是医院感染的主要病原菌，常因留置导管上生物膜的形成而引起。一旦生物膜生长在这些表面上，它们就很难被根除，因为组成细胞对许多抗生素表现出更强的抗药性。这一点，再加上感染中发现的很大比例的金黄色葡萄球菌分离株现在对包括甲氧西林和万古霉素(MRSA，VRSA)在内的多种抗生素具有耐药性基因，这清楚地表明，需要开发新的方法来对抗葡萄球菌生物被膜相关感染。哈佛大学新的耐甲氧西林金黄色葡萄球菌治疗合作项目的这个子项目专注于针对葡萄球菌生物膜的抗生物被膜剂的开发。我们最近发现了两种不同的机制来抑制生物膜的形成，包括金黄色葡萄球菌。第一种机制是基于细菌在涉及异常脂质的功能微域中组织许多与膜相关的过程的发现，即细菌具有与真核细胞中发现的类似的脂筏。干扰这些常见脂质的合成可以导致完全消除生物膜的形成，而不会对细胞产生致命影响。 第二个发现是细菌在生物膜生命周期的后期产生D-氨基酸，这些氨基酸被结合到肽聚糖中，结果是细胞从生物膜基质中释放出来，从而生物膜被分解。虽然这些过程已经在枯草芽孢杆菌中进行了详细的分析，但对于脂类合成抑制剂或D-氨基酸阻止金黄色葡萄球菌生物膜形成的机制知之甚少。为此，我们建议：1)确定金黄色葡萄球菌中脂筏的形成途径，并确定抗脂筏药物抑制生物膜形成的机制；2)确定D-氨基酸影响金黄色葡萄球菌生物膜的分子机制。

PROJECT SUMMARY (See instructions): Staphylococcus aureus is key pathogen involved in nosocomial infections, frequently due to biofilm formation on indwelling devices. Once biofilms grow on these surfaces they are difficult to eradicate because the constituent cells display increased resistance to many antibiotics. This, combined with the fact that a large percentage of S. aureus isolates identified in infections now harbor resistance genes against numerous antibiotics including methicillin and vancomycin (MRSA, VRSA), makes it clear that new ways of combating staphyloccocal biofilm-associated infections need to be developed. This subproject ofthe Harvard-wide collaborative project for new MRSA treatments is focused on the development of anti-biofilm agents that target staphyloccocal biofilms. We have recently discovered two distinct mechanisms for inhibiting biofilm formation in a broad range of organisms, including S. aureus. The first mechanism is based on the finding that bacteria organize many membrane-related processes in functional microdomains that involve unusual lipids, i.e. bacteria have lipid rafts akin to those is found in eukaryotic cells. Interfering with the synthesis of these usual lipids can lead to complete elimination of biofilm formation without a lethal effect on the cells. The second discovery is that bacteria produce D-amino acids late in the life cycle of a biofilm and that these amino acids are incorporated into the peptidoglycan with the consequence that cells are released from the biofilm matrix and the biofilm is thus disassembled. While these processes have been analyzed in detail in the bacterium Bacillus subtilis, little is known about the mechanisms by which lipid synthesis inhibitors or D-amino acids prevent biofilm formation in S. aureus. To this end, we propose to: 1) Identify the lipid raft fomiation pathway in S. aureus and determine the mechanism through which anti-lipid raft agents inhibit biofilm formation, and 2) Determine the molecular mechanism through which D-amino acids affect S. aureus biofilms.