The Antifungal Effect Of Photodynamic Therapy On Candida Albicansin Erosive Oral Lichen Planus

Objective:1. To study the detection rate of Candida albicans in erosive OLP patients.2. To compare antifungal effect of TBO-PDT with that of MB-PDT on Candida aibicans in vitro and provide a theoretical basis for the selection of photosensitizer in clinic.3. To establish optimal parameters for TBO-PDT to Candida albicans such as the TBO concentration and red light exposure dose.4. To compare the PDT sensitivity of clinical isolates with that of standard strains to when applying different light exposure doses and photosensitizer concentrations.Methods:1. We selected120erosive oral lichen planus patients and120healthy people as research subjects. After sampling by improved cotton swab method, the CHROMagar Candida was used to identify Candida albicans. Using API20C AUX system to indentify the stains that can not display specific colour on CHROMagar Candida.2. This experiment consisted four groups:Group1was TBO clinical isolates. Group2was TBO standard strains. Group3was MB and clinical isolates. Group4is MB standard strains. Within each group, there were three light exposure doses:9.6J/cm2,19.2J/cm2,28.8J/cm2. For each light exposure dose, there were four subgroups:L-P-,L-P+,L+P-,L+P+. All groups described above were with photosensitizer concentration of50μg/ml, Candida albicans suspension of1.0×106CFU/ml for PDT experiments in accordance with the conditions above. After PDT treatment, the suspension was diluted103-fold, and then50μl plated on Sabouraud dextrose-peptone agar. The Candida albicans growth were analyzed by colony forming units. 3. This experiment included two groups. Group1was TBO clinical isolates, and group2was TBO standard strains. Within each group, there were five photosensi-tizer concentration:10μg/ml,20μg/ml,30μg/ml,40μg/ml,50μg/ml. ALL groups described above with light exposure dose28.8J/cm2.Results:1. The detection rate for erosive oral lichen planus patients was51.6%. It was significantly higher than the healthy people, which was28.3%(p<0.05).2. When the light exposure dose was9.6J/cm2or19.2J/cm2, there was no significant statistical difference between TBO clinical isolates and MB clinical isolates (p>0.05), or between TBO standard strains group and MB standard strains. When the light exposure dose was28.8J/cm2, there was no significant statistical difference between TBO standard strains group and MB standard strains (p>0.05), but the statistical difference was significant between TBO clinical isolates group and MB clinical isolates (p<0.05).3. With the increasing of light exposure (9.6J/cm2、19.2J/cm2.28.8J/cm2), the survival of Candida albicans were decreased. And all of the Candida albicans were killed after28.8J/cm2red light exposure with50μg/ml of TBO. The difference was statistically significant compared with the control. Between each exposure dose group, the difference was statistically significant too (p<0.01).4. With the increasing of the concentration of TBO (10μg/ml、20μg/ml、30μg/ml、40μg/ml、50μg/ml), the survival of Candida albicans were decreased and totally inhibited in50μg/ml of TBO, and the statistical difference was significant compared to the control (p<0.01). Between each concentration group, the difference was statistically significant too (p<0.01).5. Within the same light exposure dose and photosensitizer concentration, the sensitivity of clinical isolates and standard strains to PDT was not significantly different (p>0.05).6. With the same light exposure dose and photosensitizer concentration conditions, there was no significant difference between L-P-group and L-P+group, or between L-P-group and L+P-group (p>0.05).Conclutions:1. The detection rate of Candida albicans in erosive oral lichen planus patients is significantly higher than the healthy people. This indicates that the oral microenvironment in erosive oral lichen planus patients has changed:Candida albicans is easy to adhere to their oral mucosa and then aggravate the syndrome.2. At the same light exposure dose, the clinical isolates had the same sensitivity with standard strains to PDT, which indicates that PDT antifungal therapy is equally effective in clinical isolates.3. At the dose of28.8J/cm2, the antifungal effect of TBO-PDT is better than MB-PDT, suggesting that the antifungal effects of TBO-PDT mybe better than MB-PDT in clinic.4. At the same drug concentration (50μg/ml), TBO-PDT antifungal effect is enhanced with an increasd light dose. Meanwhile, at the same light dose (28.8J/cm2), TBO-PDT antifungal effect is enhanced with an increasing drug concentration.5. Candida albicans can be inactivated with the optimal treatment parameters of50μg/ml TBO, red light630nm and28.8J/cm2light dose.