Mang Thomas S, Tayal Dharam P, Baier Robert
Department of Oral and Maxillofacial Surgery, School of Dental Medicine, University at Buffalo, Buffalo, New York 14214, USA.
Lasers Surg Med. 2012 Sep;44(7):588-96. doi: 10.1002/lsm.22050. Epub 2012 Jul 27.
Biofilm-related diseases such as caries and periodontal disease are prevalent chronic oral infections which pose significant oral and general health risks. Biofilms are sessile communities attached to surfaces. Photodynamic therapy (PDT) has been demonstrated to have a significant anti-microbial effect and presents as an alternative to treating biofilm-related disease. The aim of this study was to determine the ability of porfimer sodium induced PDT to treat localized infections of Streptococcus mutans in biofilm communities.
Reproducible biofilms were formed by S. mutans strain ATCC 27351 growing in log phase at 37°C in Brain Heart Infusion medium, circulating through flow cells at 3 ml/minute for 36-48 hours. The photosensitizer used was porfimer sodium (Photofrin®) at 125 µg/ml with biofilm immersion times of 5 minutes and increasing energy density of post-immersion laser illumination at 630 nm (100 mW/cm(2) ). Resulting effects on bacterial viability in the biofilms were tracked by monitoring alamarBlue® conversion. Supplementary data characterizing the biofilms before and after exposure to PDT were acquired by Multiple Attenuated Internal Reflection Infrared Spectroscopy (MAIR-IR).
The results of this study show that PDT using porfimer sodium and 630 nm laser light was effective in significantly reducing the viability of S. mutans biofilms. Maximum effectiveness was seen when biofilms were exposed to both photosensitizer and light versus controls. Porfimer sodium incubation times as short as 5 minutes in solutions as dilute as 25 µg/ml and illuminated with as little as 30 J/cm(2) resulted in significant decreases in viability of bacteria in biofilms. Optimum parameters appear to be 125 µg/ml porfimer sodium concentration and incubated for 5 minutes and 60 J/cm(2) of light energy density.
This study has demonstrated that significant killing of the cariogenic organism S. mutans by the combination of a photosensitizer and the appropriate wavelength of laser light was possible even when the bacteria are embedded in an extracellular matrix.
龋齿和牙周病等生物膜相关疾病是常见的慢性口腔感染，对口腔和全身健康构成重大风险。生物膜是附着于表面的固着群落。光动力疗法（PDT）已被证明具有显著的抗菌作用，是治疗生物膜相关疾病的一种替代方法。本研究的目的是确定卟吩姆钠诱导的光动力疗法治疗变形链球菌在生物膜群落中局部感染的能力。
变形链球菌ATCC 27351菌株在脑心浸液培养基中于37℃对数生长期生长，以3毫升/分钟的流速通过流动小室循环36 - 48小时，形成可重复的生物膜。使用的光敏剂为卟吩姆钠（Photofrin®），浓度为125微克/毫升，生物膜浸泡时间为5分钟，浸泡后630纳米激光照射的能量密度逐渐增加（100毫瓦/平方厘米）。通过监测alamarBlue®的转化来追踪对生物膜中细菌活力的影响。通过多重衰减全内反射红外光谱（MAIR - IR）获取暴露于光动力疗法前后生物膜特征的补充数据。
本研究结果表明，使用卟吩姆钠和630纳米激光的光动力疗法能有效显著降低变形链球菌生物膜的活力。与对照组相比，生物膜同时暴露于光敏剂和光时效果最佳。在低至25微克/毫升的溶液中卟吩姆钠孵育时间短至5分钟，并用低至30焦/平方厘米的光照，生物膜中细菌的活力就会显著降低。最佳参数似乎是卟吩姆钠浓度为125微克/毫升，孵育5分钟，光能密度为60焦/平方厘米。
本研究表明，即使细菌嵌入细胞外基质中，光敏剂与适当波长的激光联合使用也能显著杀死致龋菌变形链球菌。
