Department of Cariology, Endodontology & Pedodontology, Academic Centre of Dentistry Amsterdam, University of Amsterdam and VU University, Amsterdam, The Netherlands.
J Endod. 2011 Jan;37(1):31-5. doi: 10.1016/j.joen.2010.09.007. Epub 2010 Nov 12.
Endodontic infections are caused by polymicrobial biofilms. Therefore, novel root canal disinfectants should be evaluated not only on single-species biofilms but also on dual- or mixed-species biofilms. A simple, high-throughput assay is urgently needed for this. In this study, the application of the resazurin metabolism assay was investigated for the evaluation of a root canal disinfectant on dual-species biofilms.
Enterococcus faecalis with or without Streptococcus mutans in biofilms were formed in an active attachment biofilm model for 24 hours. Subsequently, the biofilms were treated with various concentrations of NaOCl for 1 minute. After resazurin metabolism by both organisms was confirmed, treatment efficacies using 0.0016% resazurin were evaluated.
During NaOCl treatments, resazurin metabolism displays a clear dose response, not only in single-species E. faecalis (or S. mutans) biofilms but also in dual-species biofilms. Notably, the assay revealed that the resistance of dual-species biofilms to NaOCl was 30-fold higher than in single-species E. faecalis biofilms. Viability counts on a selected NaOCl treatment (0.004%) confirmed this result and showed the increased resistance of E. faecalis in dual-species biofilms.
Clearly, the high-throughput and low cost resazurin metabolism assay has a great potential for testing novel root canal antimicrobial agents in mixed-species biofilms.
牙髓感染是由多微生物生物膜引起的。因此，新型根管消毒剂的评估不仅应针对单种生物膜，还应针对双种或混合生物膜。为此，迫切需要一种简单、高通量的检测方法。本研究探讨了 Resazurin 代谢测定法在评价根管消毒剂对双种生物膜的应用。
采用活性附着生物膜模型在 24 小时内形成粪肠球菌与变形链球菌混合生物膜或粪肠球菌单种生物膜。随后，用不同浓度的次氯酸钠处理生物膜 1 分钟。在两种生物都能代谢 Resazurin 后，用 0.0016% Resazurin 评估治疗效果。
在次氯酸钠处理过程中，Resazurin 代谢不仅在粪肠球菌（或变形链球菌）单种生物膜中，而且在双种生物膜中都呈现出明显的剂量反应。值得注意的是，该测定法显示，双种生物膜对次氯酸钠的耐药性比粪肠球菌单种生物膜高 30 倍。在选定的次氯酸钠处理（0.004%）上的活菌计数证实了这一结果，并显示了双种生物膜中粪肠球菌的耐药性增加。
显然，高通量、低成本的 Resazurin 代谢测定法在混合生物膜中测试新型根管抗菌剂具有很大的潜力。
