5-aminolevulinic Acid Photodynamic (ALA-PDT) Research On The Role Of Candida Albicans

Objective1、To investigate ALA pharmacokinetics in Candida albicans，to providea reliable basis for the prerequisite of photodynamic effect based ontopical application of5-aminolevulinic acid.2、Studying ALA-PDT antifungal effect against Candida albicans underdifferent incubation times to determine its fungicidal ability,andinvestigate the best dressing time for the treatment.3、Observing the influence of cell ultrastructure of Candida albicans byALA-PDT to Provide a theoretical basis for the study of the mechanismof ALA-PDT antifungal.4、To investigate the susceptibility of Candida albicans Subjected toPhotodynamic Therapy with FIuconazole to provide a theoretical basisfor Photodynamic therapy combined with fluconazole for the treatmentof candidiasis.Methods1、The use of confocal laser scanning microscope to detect PpⅨ producedin Candida albicans2、Determination of the number of colony forming units after ALA-PDT underdifferent incubation times by plate count method.3、Observ the influence to the cell ultrastructure of Candida albicanssubjected to ALA-PDT.4、Broth macrodilution assay were performed to investigate the differencesof susceptibility between the strain Subjected to ALA-PDT and the strainnot to with FIuconazole. Result1、PpIX present brick red fluorescence under CLSM after suspensions ofCandida strain incubated with100mM ALA in37℃in the dark.2、Different colonies are counted under different incubtion times,theminimum number of colonies are observed after incubation for30minfollowed by irradiation which is lower than other group of incubationtime,The difference was statistically significant(P<0.01),besides,the differences of the number of the colonies was not statisticallysignificant among incubation without ALA or withoutirradiation.(P=1.000)3、Under transmission electron microscope,the cell after ALA-PDT presentSwelling deformation,showing incomplete walland membrane structure.cell wall is loose,The gap between the cell membrane and cell wallsizes.incomplete cell wall structure with electron dense layers andcell membrane disappeared somewhere in some cell.4、The MIC of Candida albicans after ALA-PDT and without ALA-PDT withFluconazole were:0.125ug/ml,1ug/ml,respectly.Conclusion1、ALA can be absorpted by Candida albicans,and can be transformated into PpIX.2、ALA-PDT is Fungicidal,and the effect is strongest while incubation withALA for30min followed by irradiation,the effect disappear when theincubation without ALA or without irradiation.3、ALA-PDT affect the biological activity of strains by destroying thecell wall and cell membrane of Candida albicans.4、ALA-PDT increased the sensitivity of Candida albicans to fluconazole.Itmay provide a theoretical basis for a efficiency,low toxicityantifungal therapy which combied photodynamic therapy withfluconazole.