Anti-staphylococcal activities of A. actinomycetemcomitans dispersin B

项目摘要/摘要进行了修改，以反映上述变化：植入医疗器械的主要风险是其高感染率。定植在医疗设备上的细菌形成基质包裹的生物膜，抵抗抗菌治疗，通常很难或不可能根除。最常见的器械相关病原体金黄色葡萄球菌和表皮葡萄球菌的细胞外基质含有一种名为PNAG（聚n -乙酰氨基葡萄糖）的粘性多糖，它介导表面附着、细胞间粘附、抗生物杀灭剂和免疫逃逸。我们实验室发现了一种降解PNAG的酶（分散酶B）。初步研究表明，分散素B可抑制葡萄球菌生物膜的形成，使预形成的葡萄球菌生物膜脱离，并使葡萄球菌生物膜细胞对体外抗菌杀伤增敏。我们的假设是，分散素B将是一种临床有用的抗生物膜剂，用于治疗和预防葡萄球菌生物膜感染。本研究的目的是证明分散素B与抗生素协同作用，在体外分离和杀死金黄色葡萄球菌和表皮葡萄球菌生物膜。分散剂B将在模拟的每日抗生素导管锁定试验中进行溶液测试，并在抗感染装置涂层模型中加载到聚氨酯磁盘上，单独或与抗生素联合使用。我们计划测试的抗生素包括替加环素和万古霉素。本研究的结果将扩展我们对pnaga介导的生物膜对特定抗生素耐药机制的认识，并将证明在体内使用分散素B作为抗生物膜剂的可行性。由于分散素B不会杀死细菌或抑制它们的生长，基于分散素B的策略可能比使用传统抗生素的策略更不容易产生耐药性。

The Project Summary/Abstract was modified to reflect the changes described above: A major risk associated with implanted medical devices is their high rate of infection. Bacteria that colonize medical devices form matrix-encased biofilms that resist antimicrobial therapy and are often difficult or impossible to eradicate. The extracellular matrix of Staphylococcus aureus and Staphylococcus epidermidis, the most common device-associated pathogens, contains a sticky polysaccharide named PNAG (poly-N-acetylglucosamine) that mediates surface attachment, intercellular adhesion, biocide resistance and immune evasion. Our laboratory discovered an enzyme (dispersin B) that degrades PNAG. Preliminary studies indicate that dispersin B inhibits staphylococcal biofilm formation, detaches pre-formed staphylococcal biofilms, and sensitizes staphylococcal biofilm cells to antimicrobial killing in vitro. Our hypothesis is that dispersin B will be a clinically useful anti-biofilm agent for the treatment and prevention of staphylococcal biofilm infections in vivo. The goal of the present proposal is to demonstrate that dispersin B acts synergistically with antibiotics to detach and kill S. aureus and S. epidermidis biofilms in vitro. Dispersin B will be tested both in solution in a simulated daily antibiotic catheter lock assay, and loaded onto polyurethane disks, either alone or in combination with antibiotics, in a model for antiinfective device coatings. The antibiotics that we plan to test include tigecycline and vancomycin. The results of the proposed studies will extend our knowledge about the mechanism of PNAGmediated biofilm resistance to specific antibiotics, and will demonstrate the feasibility of using dispersin B as anti-biofilm agent in vivo. Since dispersin B does not kill bacteria or inhibit their growth, dispersin B-based strategies may be less prone to the evolution of resistance than strategies utilizing conventional antibiotics.