Tammer Ina, Reuner Julia, Hartig Roland, Geginat Gernot
Institute of Medical Microbiology, Otto von Guericke University, 39120 Magdeburg, Germany.
J Antimicrob Chemother. 2014 May;69(5):1282-5. doi: 10.1093/jac/dkt521. Epub 2014 Jan 20.
Silver exhibits excellent antimicrobial properties and is used to protect medical devices from microbial colonization. Because few data are available on the influence of silver coating of vascular prostheses on Candida biofilm formation, this study aimed to investigate the effect of silver on yeast biofilm formation in an in vitro model.
Prosthesis material was co-cultivated with two different strains of Candida albicans and the effect of silver on attachment and the growth of biofilms was monitored by microscopy and by quantification of cfu and mitochondrial dehydrogenase activity.
Silver collagen-coated vascular prostheses significantly reduced C. albicans biofilm formation in serum-free medium. Paradoxically, in the presence of 50% serum, silver increased the growth of biofilms on silver-containing prostheses 2- to 10-fold compared with silver-free prostheses. Silver ion concentrations between 1.7 and 0.17 mg/L, corresponding roughly to 1/20 to 1/200 of the MIC of silver nitrate, stimulated biofilm formation by C. albicans.
Serum proteins reduced the concentration of silver ions delivered from the surface of vascular prostheses to a subinhibitory level, which stimulated the attachment and biofilm formation of C. albicans on grafts. Silver collagen coating therefore seems to be unsuitable for the prevention of growth of C. albicans on vascular prostheses under physiological conditions.
银具有出色的抗菌性能，可用于保护医疗设备免受微生物定植。由于关于血管假体银涂层对念珠菌生物膜形成影响的数据较少，本研究旨在体外模型中探究银对酵母生物膜形成的影响。
将假体材料与两种不同的白色念珠菌菌株共同培养，并通过显微镜检查以及对菌落形成单位和线粒体脱氢酶活性的定量分析，监测银对生物膜附着和生长的影响。
银胶原蛋白涂层的血管假体在无血清培养基中显著减少了白色念珠菌生物膜的形成。矛盾的是，在存在50%血清的情况下，与无银假体相比，银使含银假体上生物膜的生长增加了2至10倍。1.7至0.17mg/L的银离子浓度，大致相当于硝酸银最低抑菌浓度的1/20至1/200，刺激了白色念珠菌生物膜的形成。
血清蛋白将从血管假体表面释放的银离子浓度降低到亚抑制水平，这刺激了白色念珠菌在移植物上的附着和生物膜形成。因此，在生理条件下，银胶原蛋白涂层似乎不适用于预防白色念珠菌在血管假体上生长。
