Antibiotic resistance of S. aureus biofilms

描述(申请人提供)：金黄色葡萄球菌是生物被膜相关感染的重要原因，如心内膜炎、慢性骨髓炎、涉及晶状体植入物的角膜感染以及与医疗器械相关的感染。涉及葡萄球菌生物膜的感染通常很难用抗生素治疗，而且可能会复发，或者需要手术切除受感染的设备或组织。临床实验室中使用的抗生素敏感性测试衡量的是浮游细菌或自由漂浮细菌的抗药性，并没有考虑到金黄色葡萄球菌生物膜对大多数抗生素的抗药性明显高于浮游细菌的事实。目前，生物膜对抗生素治疗的耐受性还不是很清楚。该项目的长期目标是确定葡萄球菌生物被膜的特性，使其对抗菌素化疗耐药。该项目的近期目标是评估聚N-乙酰氨基葡萄糖(PNAG)在抗生素耐药性中的作用，PNAG在金黄色葡萄球菌生物被膜的形成中起着关键作用。首先，将表征PNAG表达对浮游细菌耐药性的影响。下一步，将实施一个非PNAG的生物膜模型，该模型基于细菌通过蛋白A/Fc-受体相互作用进行交联，以便将PNAG在生物膜抗生素耐药性中的作用与其在生物膜形成中的作用分开。此外，还将通过共聚焦显微镜分析PNAG对荧光标记抗生素在生物膜中渗透的影响。最后，将描述PNAG和通常用于治疗金黄色葡萄球菌感染的抗生素之间的相互作用。我们推测PNAG在金黄色葡萄球菌生物被膜的耐药性中起着重要的作用，因为它是金黄色葡萄球菌对抗生素渗透的物理屏障，我们期待对PNAG在金黄色葡萄球菌对抗生素耐药性中的作用的了解将促进用于对抗这些感染的治疗方法的发展。

DESCRIPTION (provided by applicant): S. aureus is an important cause of biofilm-related infections such as endocarditis, chronic osteomyelitis, corneal infections involving lens implants, and medical device-related infections. Infections involving staphylococcal biofllms are often very difficult to treat with antibiotics and may be recurrent or require surgical removal of the infected device or tissue. Antibiotic susceptibility tests used in the clinical laboratory measure the resistance of planktonic or free-floating bacteria and do not account for the fact that S. aureus biofilms are significantly more resistant to most antibiotics than planktonic bacteria. The characteristics of biofilms that make them refractory to antibiotic therapy are not well understood at this time. The long-term objective of this project is to characterize the properties of staphylococcal biofilms that make them refractory to antimicrobial chemotherapy. The immediate goal of the proposed project is to assess the role in antibiotic resistance of poly-N-acetyl glucosamine (PNAG), which plays a critical role in S. aureus biofilm formation. First, the influence of PNAG expression on antibiotic resistance of planktonic bacteria will be characterized. Next, a PNAG-independent biofilm model, based on the cross linking of bacteria via protein A / Fc-receptor interactions, will be implemented so that the role of PNAG in biofilm antibiotic resistance can be separated from its role in biofilm formation. In addition, the effect of PNAG on the penetration of fluorescently labeled antibiotics throughout biofilms will be analyzed by confocal microscopy. Finally, the interaction between PNAG and antibiotics commonly used to treat S. aureus infections will be characterized. We hypothesize that PNAG plays an important role in the resistance of S. aureus biofilms by acting as a physical barrier against antibiotic penetration and expect that knowledge of the role of PNAG in S. aureus biofilm resistance to antibiotics will advance the development of therapies used to combat these infections.