Kranz Stefan, Guellmar Andre, Völpel Andrea, Gitter Burkhard, Albrecht Volker, Sigusch Bernd W
Department of Conservative Dentistry, Friedrich Schiller University, Jena, Germany.
Lasers Surg Med. 2011 Mar;43(3):241-8. doi: 10.1002/lsm.21046.
Enterococcus faecalis is frequently found in persistent endodontic infections. In this context, the antimicrobial photodynamic therapy (aPDT) could become a modern alternative to existing antibacterial treatment approaches. The aim of this study was to investigate the effect of aPDT on E. faecalis using the photosensitizer (PS) 5,10,15,20-tetra(m-hydroxyphenyl)chlorin (mTHPC) enriched in liposomes.
Enterococcus faecalis was cultivated in Schaedler submerged culture for 24 hours, then isolated and adjusted in PBS to 10(8) cells/ml. The bacterial suspension was pipetted into a black microtitration plate and incubated for 15 minutes in the dark with mTHPC in various concentrations (10, 30, and 50 µM). The photosensitized suspensions were subjected to laser light (652 nm) at a light fluence of 100 J cm(-2) (test group A). In addition, the suspension sensitized with 50 µM mTHPC was irradiated with 25, 50, and 75 J cm(-2) (test group B). The following controls were used: non-irradiated bacterial suspension in the absence of mTHPC (C); irradiated bacterial suspension in the absence of mTHPC (D); non-irradiated bacterial suspension incubated with mTHPC (E). Dilution series (10(0)-10(-6)) were made of all groups and applied on Schaedler agar. After anerobic cultivation (4 days), the colony-forming units (CFU/ml) were determined.
Enterococcus faecalis was suppressed completely after incubation with 50 µM mTHPC and illumination with 100 J cm(-2). Photodynamic treatment with 10 and 30 µM mTHPC caused reduction in CFU by 5.8 and 6.7 log-units. The application of an energy fluence <100 J cm(-2) resulted in a decline of antibacterial efficiency. Irradiation of the non-photosensitized solution showed no suppressing impact. Incubation of the PS without additional irradiation caused a maximal reduction in CFU by 1.5 log-units.
The results show that aPDT using the PS mTHPC incorporated in liposomes could be a new approach to adjuvant treatment of endodontic infections with E. faecalis.
粪肠球菌常见于持续性牙髓感染中。在此背景下，抗菌光动力疗法（aPDT）可能成为现有抗菌治疗方法的一种现代替代方案。本研究的目的是使用富含脂质体的光敏剂（PS）5,10,15,20-四（间羟基苯基）氯卟啉（mTHPC）来研究aPDT对粪肠球菌的作用。
将粪肠球菌在 Schaedler 液体培养基中培养 24 小时，然后分离并在 PBS 中调整至 10⁸ 个细胞/ml。将细菌悬液移液至黑色微量滴定板中，并在黑暗中与不同浓度（10、30 和 50 μM）的 mTHPC 孵育 15 分钟。将光敏化悬液以 100 J/cm² 的光通量照射激光（652 nm）（试验组 A）。此外，用 50 μM mTHPC 致敏的悬液分别以 25、50 和 75 J/cm² 进行照射（试验组 B）。使用以下对照：在无 mTHPC 的情况下未照射的细菌悬液（C）；在无 mTHPC 的情况下照射的细菌悬液（D）；与 mTHPC 孵育的未照射细菌悬液（E）。对所有组进行稀释系列（10⁰ - 10⁻⁶）并接种于 Schaedler 琼脂上。经过厌氧培养（4 天）后，测定菌落形成单位（CFU/ml）。
用 50 μM mTHPC 孵育并以 100 J/cm² 光照后，粪肠球菌被完全抑制。用 10 和 30 μM mTHPC 进行光动力治疗使 CFU 减少了 5.8 和 6.7 个对数单位。能量通量<100 J/cm² 的应用导致抗菌效率下降。未光敏化溶液的照射未显示抑制作用。在无额外照射的情况下孵育 PS 导致 CFU 最大减少 1.5 个对数单位。
结果表明，使用脂质体包裹的 PS mTHPC 的 aPDT 可能是辅助治疗粪肠球菌引起的牙髓感染的一种新方法。
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