Mulley Geraldine, Jenkins A Tobias A, Waterfield Nicholas R
School of Biological Sciences, University of Reading, Reading, United Kingdom.
Department of Chemistry, University of Bath, Claverton Down, Bath, United Kingdom.
PLoS One. 2014 Apr 11;9(4):e94409. doi: 10.1371/journal.pone.0094409. eCollection 2014.
There has been a recent surge in the use of silver as an antimicrobial agent in a wide range of domestic and clinical products, intended to prevent or treat bacterial infections and reduce bacterial colonization of surfaces. It has been reported that the antibacterial and cytotoxic properties of silver are affected by the assay conditions, particularly the type of growth media used in vitro. The toxicity of Ag+ to bacterial cells is comparable to that of human cells. We demonstrate that biologically relevant compounds such as glutathione, cysteine and human blood components significantly reduce the toxicity of silver ions to clinically relevant pathogenic bacteria and primary human dermal fibroblasts (skin cells). Bacteria are able to grow normally in the presence of silver nitrate at >20-fold the minimum inhibitory concentration (MIC) if Ag+ and thiols are added in a 1:1 ratio because the reaction of Ag+ with extracellular thiols prevents silver ions from interacting with cells. Extracellular thiols and human serum also significantly reduce the antimicrobial activity of silver wound dressings Aquacel-Ag (Convatec) and Acticoat (Smith & Nephew) to Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli in vitro. These results have important implications for the deployment of silver as an antimicrobial agent in environments exposed to biological tissue or secretions. Significant amounts of money and effort have been directed at the development of silver-coated medical devices (e.g. dressings, catheters, implants). We believe our findings are essential for the effective design and testing of antimicrobial silver coatings.
最近，银作为抗菌剂在各种家用和临床产品中的使用激增，旨在预防或治疗细菌感染并减少表面细菌定植。据报道，银的抗菌和细胞毒性特性受检测条件影响，特别是体外使用的生长培养基类型。Ag⁺ 对细菌细胞的毒性与对人类细胞的毒性相当。我们证明，谷胱甘肽、半胱氨酸和人类血液成分等生物相关化合物可显著降低银离子对临床相关病原菌和原代人皮肤成纤维细胞（皮肤细胞）的毒性。如果以1:1的比例添加Ag⁺ 和硫醇，细菌能够在硝酸银存在下以高于最低抑菌浓度（MIC）20倍的浓度正常生长，因为Ag⁺ 与细胞外硫醇的反应可防止银离子与细胞相互作用。细胞外硫醇和人血清在体外也显著降低了含银伤口敷料Aquacel-Ag（康维德公司）和Acticoat（施乐辉公司）对金黄色葡萄球菌、铜绿假单胞菌和大肠杆菌的抗菌活性。这些结果对于在暴露于生物组织或分泌物的环境中使用银作为抗菌剂具有重要意义。大量资金和精力已投入到开发镀银医疗器械（如敷料、导管、植入物）上。我们相信我们的发现对于抗菌银涂层的有效设计和测试至关重要。
