中文摘要：

目的研究纳米银对引起牙科根管治疗失败的致病菌粪肠球菌、溶血链球菌的抑菌、杀菌和抑制生物被膜形成的作用，为纳米银应用于根管消毒提供实验依据。方法微稀释法测定纳米银及其对照药物对粪肠球菌最小抑菌浓度（MIC）和最小杀菌浓度（MBC）、对溶血链球菌的MIC，评价纳米银的抗菌作用。结晶紫染色法检测粪肠球菌ATCC51299和粪肠球菌ATCC29212，溶血链球菌ATCC6644和溶血链球菌ATCC19615生物被膜形成情况，评价纳米银及对照药物对生物被膜形成的抑制作用。结果纳米银对25株粪肠球菌有较好的抑制作用，MIC range为37．5～75μmol／L，MIC50和MIC90均为75μmol／L；对24株链球菌也有较好的抑制作用，MICrange为18．75～37．5μmol／L，MIC50和MIC90均为37．5μmol／L。纳米银对粪肠球菌ATCC51299和粪肠球菌ATCC29212显示较好的杀菌活性，最小杀菌浓度和最小抑菌浓度比值（MBC／MIC）为2。同时，纳米银对粪肠球菌ATCC51299和粪肠球菌ATCC29212，溶血链球菌ATCC6644和溶血链球菌ATCC19615生物被膜形成有明显抑制作用，2倍MIC浓度的纳米银对生物被膜形成的抑制率为79％～94％。

英文摘要：

Objective To evaluate the bacteriostatic, bactericidal and anti-biofilm formation effects of nanosilver against Enterococcus faecalis and hemolytic Streptococcus spp., the problematic organisms causing root canal treatment failure, and to provide experimental evidence for using nanosilver on root canal disinfection. Methods The minimum inhibitory concentration （MIC）, the minimum bactericidal concentration （MBC） of nanosilver and the control drugs were determined by broth microdilution method. The anti-biofilm formation effect of nanosilver and the control drugs was determined by crystal violet assay. Results Nanosilver demonstrated satisfactory antibacterial activities against 25 Enterococcus faecalis, with MICrange of 37.5-75μmol/L, MIC50 and MIC90 both of 75μmol/L. Nanosilver also showed satisfactory antibacterial activities against hemolytic Streptococcus spp., with MIC range of 18.75-37.5 μmol/L, MIC50 and MIC90 both of 37.5 μmol/L. MBC determination results showed that the MBC/MIC ratios of nanosilver against E. faecalis ATCC51299 and E. faecalis ATCC29212 were both 2, suggesting good bactericidal activity of nanosilver. Nanosilver showed good anti-biofilm formation activity against E. faecalis ATCC51299, E. faecalis ATCC29212, S. dysgalactiae ATCC6644 and S. pyogenes ATCC19615, nanosilver at concentrations of 2MIC inhibited the biofilm formation by 79%-94%.