Faculty of Dentistry, Department of Restorative Dentistry, National University of Singapore, Singapore.
Int Endod J. 2010 Nov;43(11):978-87. doi: 10.1111/j.1365-2591.2010.01717.x. Epub 2010 Aug 16.
To evaluate the efficacy of light-activated disinfection (LAD) using methylene blue (MB) and a non-coherent light source on gram-positive and gram-negative bacteria in different growth modes. The influence of different photosensitizer (PS) formulations in the MB-mediated LAD of biofilms was also evaluated.
Light-activated disinfection using MB was tested on Enterococcus faecalis in a planktonic suspension, coaggregated suspension and mono-species biofilms and on Pseudomonas aeruginosa in a planktonic suspension and mono-species biofilms. Further, the difference in susceptibility of E. faecalis and P. aeruginosa biofilms to LAD with modified PS formulations was assessed by conventional culturing methods and confocal laser scanning microscopy (CLSM).
Higher energy dose was required for LAD of bacteria in a coaggregated suspension and in biofilm compared to their planktonic counterparts. Biofilm mode of growth offered the greatest resistance to LAD in both the tested strains of pathogens (P<0.001). Gram-positive E. faecalis was more susceptible to LAD than the gram-negative P. aeruginosa, and the use of modified PS formulations was found to enhance the efficacy of LAD to destroy the biofilm (P<0.001).
Bacterial growth modes play a vital role in influencing the susceptibility to LAD in a dose-dependent manner. The nature of the PS formulation influences the susceptibility of biofilms to LAD.
评估使用亚甲蓝（MB）和非相干光源对不同生长模式下革兰氏阳性菌和革兰氏阴性菌的光活化消毒（LAD）的疗效。还评估了不同光敏剂（PS）配方在 MB 介导的生物膜 LAD 中的影响。
在浮游悬液、共聚悬浮液和单种生物膜中的粪肠球菌和浮游悬液和单种生物膜中的铜绿假单胞菌上测试了使用 MB 的光活化消毒。此外，通过常规培养方法和共聚焦激光扫描显微镜（CLSM）评估了改良 PS 配方对粪肠球菌和铜绿假单胞菌生物膜对 LAD 敏感性的差异。
与浮游相对照，共聚悬浮液和生物膜中的细菌的 LAD 需要更高的能量剂量。在两种测试病原体菌株中，生物膜生长方式为 LAD 提供了最大的抵抗力（P<0.001）。革兰氏阳性的粪肠球菌比革兰氏阴性的铜绿假单胞菌更容易受到 LAD 的影响，并且发现改良 PS 配方的使用增强了 LAD 破坏生物膜的功效（P<0.001）。
细菌生长方式以剂量依赖的方式在影响对 LAD 的敏感性方面起着至关重要的作用。PS 配方的性质影响生物膜对 LAD 的敏感性。
