Vanzieleghem Thomas, Herman-Bausier Philippe, Dufrene Yves F, Mahillon Jacques
†Laboratory of Food and Environmental Microbiology, Earth and Life Institute (ELI) and ‡ Institute of Life Sciences, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium.
Langmuir. 2015 Apr 28;31(16):4713-21. doi: 10.1021/acs.langmuir.5b00360. Epub 2015 Apr 13.
Staphylococcus epidermidis is a world-leading pathogen in healthcare facilities, mainly causing medical device-associated infections. These nosocomial diseases often result in complications such as bacteremia, fibrosis, or peritonitis. The virulence of S. epidermidis relies on its ability to colonize surfaces and develop thereupon in the form of biofilms. Bacterial adherence on biomaterials, usually covered with plasma proteins after implantation, is a critical step leading to biofilm infections. The cell surface protein SdrG mediates adhesion of S. epidermidis to fibrinogen (Fg) through a specific "dock, lock, and latch" mechanism, which results in greatly stabilized protein-ligand complexes. Here, we combine single-molecule, single-cell, and whole population assays to investigate the extent to which the surface density of SdrG determines the ability of S. epidermidis clinical strains HB, ATCC 35984, and ATCC 12228 to bind to Fg-coated surfaces. Strains that showed enhanced adhesion on Fg-coated polydimethylsiloxane (PDMS) were characterized by increased amounts of SdrG proteins on the cell surface, as observed by single-molecule analysis. Consistent with previous reports showing increased expression of SdrG following in vivo exposure, this work provides direct evidence that abundance of SdrG on the cell surface of S. epidermidis strains dramatically improves their ability to bind to Fg-coated implanted medical devices.
表皮葡萄球菌是医疗机构中全球领先的病原体，主要引起与医疗器械相关的感染。这些医院内疾病常导致菌血症、纤维化或腹膜炎等并发症。表皮葡萄球菌的毒力依赖于其在表面定植并在其上形成生物膜的能力。细菌在生物材料上的黏附是导致生物膜感染的关键步骤，植入后生物材料表面通常覆盖有血浆蛋白。细胞表面蛋白SdrG通过特定的“对接、锁定和闩锁”机制介导表皮葡萄球菌与纤维蛋白原（Fg）的黏附，这导致蛋白-配体复合物得到极大稳定。在此，我们结合单分子、单细胞和全群体分析，以研究SdrG的表面密度在多大程度上决定表皮葡萄球菌临床菌株HB、ATCC 35984和ATCC 12228与Fg包被表面结合的能力。通过单分子分析观察到，在Fg包被的聚二甲基硅氧烷（PDMS）上表现出增强黏附的菌株，其细胞表面SdrG蛋白的量增加。与之前关于体内暴露后SdrG表达增加的报道一致，这项工作提供了直接证据，即表皮葡萄球菌菌株细胞表面SdrG的丰度显著提高了它们与Fg包被的植入式医疗器械结合的能力。
