Wood Simon, Metcalf Daniel, Devine Deirdre, Robinson Colin
Division of Oral Biology, Leeds Dental Institute, University of Leeds, UK.
J Antimicrob Chemother. 2006 Apr;57(4):680-4. doi: 10.1093/jac/dkl021. Epub 2006 Feb 7.
The purpose of this study was to evaluate the clinical plaque disclosing agent erythrosine as a photosensitizer in the photodynamic killing of the oral bacterium Streptococcus mutans grown as a biofilm.
S. mutans biofilms of 200 microm thickness were grown in a constant-depth film fermenter. In addition to determining localization of the photosensitizer within biofilms using confocal laser scanning microscopy (CLSM), we compared the bacterial killing efficacy of erythrosine with that of two well-characterized photosensitizers, methylene blue (MB) and photofrin. Incubations were carried out with each photosensitizer (22 microM), and irradiation was for 15 min using a 400 W white light source.
The CLSM results showed that erythrosine is taken up into S. mutans biofilms, where it is associated with the biomass of the biofilm rather than the fluid-filled channels and voids. Comparison of the cell killing efficacy of erythrosine in S. mutans biofilms of different ages showed that erythrosine was 1-2 log(10) more effective at killing biofilm bacteria than photofrin and 0.5-1 log(10) more effective than MB. The results were statistically significant (P < 0.01). Photodynamic therapy (PDT) with all three photosensitizers was increasingly effective as biofilm age increased, suggesting that temporal changes in biofilm architecture and composition affect susceptibility to PDT.
PDT using erythrosine as photosensitizer shows excellent potential as a treatment for oral plaque biofilms.
本研究旨在评估临床菌斑显示剂赤藓红作为光敏剂在光动力杀灭变形链球菌生物膜中的效果。
在恒深膜发酵罐中培养厚度为200微米的变形链球菌生物膜。除了使用共聚焦激光扫描显微镜（CLSM）确定光敏剂在生物膜中的定位外，我们还比较了赤藓红与两种已充分表征的光敏剂亚甲蓝（MB）和卟吩姆钠的杀菌效果。每种光敏剂（22微摩尔）进行孵育，使用400瓦白光源照射15分钟。
CLSM结果表明，赤藓红被吸收到变形链球菌生物膜中，它与生物膜的生物量相关，而不是与充满液体的通道和空隙相关。比较不同年龄的变形链球菌生物膜中赤藓红的细胞杀伤效果表明，赤藓红杀灭生物膜细菌的效果比卟吩姆钠高1 - 2个对数（10），比MB高0.5 - 1个对数（10）。结果具有统计学意义（P < 0.01）。随着生物膜年龄增加，使用所有三种光敏剂的光动力疗法（PDT）效果越来越好，这表明生物膜结构和组成的时间变化会影响对PDT的敏感性。
使用赤藓红作为光敏剂的PDT作为治疗口腔菌斑生物膜的方法显示出巨大潜力。
