結合光動力殺菌與抗真菌藥物於白色念珠菌的生物效應探討

Abstract

白色念珠菌(Candida albicans)為院內感染的伺機性真菌之一，目前治療真菌感染主要還是以抗真菌藥物為主，但大多有副作用及抗藥性問題產生。光動力殺菌Photodynamic inactivation (PDI)是一種用來解決菌體產生抗藥性問題的治療方式，其作用方式為藉由光感物質在光激發下產生單態氧及自由基來破壞菌體，進而導致菌體死亡。 實驗室先前針對懸浮培養的白色念珠菌以光動力結合抗真菌藥物Fluconazole，發現可提高Fluconazole的藥物作用，但在白色念珠菌生物膜以相同模式進行殺菌，卻無法提升殺菌效果。於此，本研究分別分析光動力殺菌後的生物膜菌體生長曲線、菌絲的生成能力、胞外聚合物厚度，以及配合caspofungin，推論光動力殺菌結合抗真菌藥物對白色念珠菌的生物膜殺菌效果不佳，可能和光動力殺菌的效果與抗真菌藥物的性質有關。另外以5-Aminolevulinic acid (5-ALA)進行光動力殺菌，結合抗真菌藥物也可在懸浮菌體提高殺菌效果。未來將以5-ALA來探討是否因粒線體受損導致菌絲生成受到影響，再加入抗真菌藥物可以提升殺菌效果，以探討光動力殺菌結合抗真菌藥物的殺菌機制。

Candida albicans is an opportunistic fungus in hospital infection. Antifungal drugs are mainly used for the treatment of fungal infection nowadays. However, there are side effects and drug resistance problems. Photodynamic inactivation (PDI) is one of the alternative treatments used to overcome the problem of drug resistance. The principle of PDI is to combine photosensitizer and light to produce reactive oxygen species that are toxic to pathogens. Previous studies in our laboratory found that combination of PDI and Fluconazole could increase the antifungal activity against suspension of C. albicans; however, the effect is not significant against C. albicans biofilm. In this study, we analyzed the growth curves of biofilm, the ability of hyphae formation and the thickness of extracellular polymeric substances (EPS) after PDI. Meanwhile, another antifungal drug, caspofungin was used to combine with PDI to study the antifungal activity against suspension and biofilm of C. albicans. We found the ineffectiveness of PDI combined with fluconazole against biofilm might relate to the effect of PDI and the action mechanism of antifungal drugs. Furthermore, we found that the combination of a photosensitizer precursor, 5-Aminolevulinic acid (5-ALA), and antifungal drugs could also increase the antifungal effect against the suspension of C. albicans.