In vitro Effectiveness of Photodynamic Antimicrobial Therapy against C. albicans
Photodynamic antimicrobial therapy (PACT) is a treatment that uses specific wavelength light in order to cause cellular toxicity through the activation of a photosensitizing agent in the presence of oxygen. PACT has been employed in vitro studies to kill Candida albicans. Objective: The aim of the present study was to evaluate the effect of PACT on the viability of C. albicans (ATCC 10231), using toluidine blue O (TBO) as photosensitizer and a light emitting diode (LED, 630 nm) as light source. Methods: After adjust to 0.5 McFarland standard, 100 ìl C. albicans in broth were used in each one experimental condition as follows: (i) untreated C. albicans suspensions; (ii) C. albicans suspensions incubated with TBO without irradiation; (iii) C. albicans suspensions irradiated with 24 J/cm2 (1 min), 72 J/cm2 (3 min) or 120 J/cm2 (5 min) without TBO pre-incubation; and (iv) C. albicans suspensions incubated with TBO and irradiated with 24 J/cm2, 72 J/cm2 or 120 J/cm2. TBO 0.00025% was used to sensitize bacteria for 5 min in dark conditions. Immediately after, C. albicans were plated onto Sabouraud agar dishes for 48 h at 37oC to determine CFU counts. Results: There were significant differences among the groups (p<0.05). PACT using the conditions tested was effective in reducing the number of C. albicans when the samples were irradiated for 1 min and 3 min with LED. The number of CFU/ml was significantly reduced after the therapy, and the results of de control groups were depended on the irradiation time used. Conclusion: Values of CFU/mL were significantly decreased after using the different parameters of PACT. Therefore, C. albicans in broth can be killed after the use of PACT in vitro conditions. Further in vitro and in situ studies must be performed to show the action of PACT on C. albicans biofilms.