乳酸链球菌素和氟化钠对变异链球菌的协同作用研究

In vitro synergistic evaluation of Nisin and NaF on Streptococcus mutans

目的:研究乳酸链球菌素(Nisin)与氟化钠(NaF)联合应用对变异链球菌(S.mutans)的影响。方法:采用微量肉汤法测量Nisin与NaF对变异链球菌的最小抑菌浓度(MIC),利用棋盘法计算分级抑菌浓度指数(FIC)。将同一MIC浓度的NaF和Nisin复配成NF,测量NF对变异链球菌产酸和耐酸的抑制效果。采用结晶紫染色测定NF抑制生物膜形成的能力,以及对已形成生物膜的破坏和分散作用,激光共聚焦显微镜观察生物膜结构变化。结果:NaF和Nisin的MIC分别为0.6 mg/mL和20 mg/mL,两者的FIC为0.75。1/8×MIC的NF对产酸和生物膜形成的抑制显著高于1/4×MIC的NaF和Nisin(P<0.05),对已形成的生物膜无分散作用。1/2×MIC NF可以比1×MIC的NaF和Nisin更显著地破坏生物膜内变异链球菌的耐酸性。2×MIC浓度下,NF、NaF、Nisin对已形成的生物膜结构造无明显破坏。结论:Nisin和NaF对变异链球菌的增殖以及产酸、耐酸和生物膜形成具有协同的抑制作用。

Objective:To study the effects of the combined application of NaF and Nisin on Streptococcus mutans(S.mutans).Methods:The minimum inhibitory concentration(MIC)of Nisin and NaF against S.mutans was determined by microdilution method respectively.The fractional inhibitory concentration(FIC)was calculated by checkerboard method.The inhibition effect of the combination of NaF and Nisin at(NF)the same MIC concentration on acid production and acid resistance of S.mutans was detected.Crystal violet staining was used to detect the effects of NF in the inhibition of the biofilm formation,and the damage and dispersion of the established biofilms.The changes of the biofilms were observed by CLSM.Results:The MIC of NaF and Nisin was 0.6 mg/mL and 20 mg/mL respectively.The FIC was 0.75.The 1/8×MIC NF showed significantly higher inhibition on acid production and biofilm formation than 1/4×MIC NaF or Nisin(P<0.05),but it has no obvious dispersion effect on established biofilms.The 1/2×MIC NF showed stronger inhibition effect on the acid resistance of S.mutans in the membrane than 1×MIC NaF or Nisin(P<0.05).At the concentration of 2×MIC,any component didn't cause obvious damage on the established biofilm structure.Conclusion:Nisin and NaF have synergistic inhibitory effects on the proliferation,acid production,acid resistance and biofilm formation of S.mutans.