Jori Giulio, Fabris Clara, Soncin Marina, Ferro Stefania, Coppellotti Olimpia, Dei Donata, Fantetti Lia, Chiti Giacomo, Roncucci Gabrio
Department of Biology, University of Padova, Via Ugo Bassi 58B, 35121 Padova, Italy.
Lasers Surg Med. 2006 Jun;38(5):468-81. doi: 10.1002/lsm.20361.
Photodynamic therapy (PDT) appears to be endowed with several favorable features for the treatment of infections originated by microbial pathogens, including a broad spectrum of action, the efficient inactivation of antibiotic-resistant strains, the low mutagenic potential, and the lack of selection of photoresistant microbial cells. Therefore, intensive studies are being pursued in order to define the scope and field of application of this approach.
Optimal cytocidal activity against a large variety of bacterial, fungal, and protozoan pathogens has been found to be typical of photosensitizers that are positively charged at physiological pH values (e.g., for the presence of quaternarized amino groups or the association with polylysine moieties) and are characterized by a moderate hydrophobicity (n-octanol/water partition coefficient around 10). These photosensitizers in a micromolar concentration can induce a >4-5 log decrease in the microbial population after incubation times as short as 5-10 minutes and irradiation under mild experimental conditions, such as fluence-rates around 50 mW/cm2 and irradiation times shorter than 15 minutes.
PDT appears to represent an efficacious alternative modality for the treatment of localized microbial infections through the in situ application of the photosensitizer followed by irradiation of the photosensitizer-loaded infected area. Proposed clinical fields of interest of antimicrobial PDT include the treatment of chronic ulcers, infected burns, acne vulgaris, and a variety of oral infections.
光动力疗法（PDT）似乎具有治疗微生物病原体引起的感染的几个有利特性，包括广泛的作用谱、有效灭活抗生素耐药菌株、低诱变潜力以及不会筛选出光抗性微生物细胞。因此，正在进行深入研究以确定该方法的应用范围和领域。
已发现，在生理pH值下带正电荷（例如，由于存在季铵化氨基或与聚赖氨酸部分结合）且具有适度疏水性（正辛醇/水分配系数约为10）的光敏剂，对多种细菌、真菌和原生动物病原体具有典型的最佳杀细胞活性。这些光敏剂在微摩尔浓度下，在温和的实验条件下（如光通量率约为50 mW/cm²且照射时间短于15分钟），孵育5 - 10分钟后照射，可使微生物数量减少>4 - 5个对数。
通过原位应用光敏剂，随后对负载光敏剂的感染区域进行照射，光动力疗法似乎是治疗局部微生物感染的一种有效替代方式。抗菌光动力疗法提议的临床关注领域包括治疗慢性溃疡、感染性烧伤、寻常痤疮以及多种口腔感染。
