Radcliffe Charlotte E, Akram Noreen C, Hurrell Fiona, Drucker David B
Oral Microbiology Laboratory, Turner Dental School, University of Manchester, Higher Cambridge Street, Manchester M15 6FH, UK.
J Dent. 2002 Sep-Nov;30(7-8):325-31. doi: 10.1016/s0300-5712(02)00046-5.
It is hypothesised that exogenous nitrite acidified by metabolic products of acidogenic bacteria in the mouth will be converted to products which inhibit growth of the bacteria in question which contribute to dental caries.
The aims of this study were (1) to test the activity of both sodium nitrate and sodium nitrite at differing concentrations on the ability of Streptococcus mutans to lower the pH of its surroundings and hence (2) to determine whether either nitrate or nitrite might be bactericidal or bacteriostatic against S. mutans.
S. mutans NCTC 10449(T) was cultured in a liquid medium to which either sodium nitrate or sodium nitrite was added to a final concentration of 0.0, 0.2, 2.0, 20 or 200 mM, of which the first acted as a test substance negative control. After 24 h, the cultures were streaked onto agar to test for growth and the remaining culture used for pH measurement. The Mann-Whitney U-Test was used for statistical comparison of pH values.
Nitrite at concentrations of 20 and 200 mM had a highly significant inhibitory effect (p < 0.001) on the ability of S. mutans NCTC 10449(T) to lower pH. Moreover, bacteria that had been subjected to these levels of nitrite were unable to recover on solid medium. Nitrate had no such effect on either the growth of the bacteria or on their ability to lower pH.
It is concluded that nitrite, at final concentrations of either 20 or 200 mM, is both bactericidal and anti-acidogenic with respect to S. mutans, while lower concentrations of nitrite and all concentrations of nitrate are ineffective. Nitrite might be worthy of consideration as a mouth-rinse constituent.
据推测，口腔中产酸菌的代谢产物酸化的外源性亚硝酸盐会转化为抑制导致龋齿的相关细菌生长的产物。
本研究的目的是（1）测试不同浓度的硝酸钠和亚硝酸钠对变形链球菌降低其周围环境pH值能力的影响，从而（2）确定硝酸盐或亚硝酸盐是否对变形链球菌具有杀菌或抑菌作用。
将变形链球菌NCTC 10449(T)在液体培养基中培养，向其中添加硝酸钠或亚硝酸钠，终浓度分别为0.0、0.2、2.0、20或200 mM，其中第一个作为测试物质阴性对照。24小时后，将培养物划线接种到琼脂上以测试生长情况，剩余培养物用于pH值测量。使用曼-惠特尼U检验对pH值进行统计比较。
浓度为20和200 mM的亚硝酸盐对变形链球菌NCTC 10449(T)降低pH值的能力具有高度显著的抑制作用（p < 0.001）。此外，经受这些亚硝酸盐水平的细菌在固体培养基上无法恢复生长。硝酸盐对细菌的生长及其降低pH值的能力均无此影响。
得出结论，终浓度为20或200 mM的亚硝酸盐对变形链球菌具有杀菌和抗产酸作用，而较低浓度的亚硝酸盐和所有浓度的硝酸盐均无效。亚硝酸盐可能值得作为漱口水成分加以考虑。
