Graphical Brief description of the procedures carried out in this study. In vivo and in vitro antibacterial photodynamic therapy (aPDT) studies, where aPDT mediated by C-DOTS and blue LED light against S. aureus was evaluated.

This study evaluated the effectiveness of antimicrobial photodynamic therapy (aPDT) in the treatment of oral candidiasis in a murine model using Photodithazine^® (PDZ). This model of oral candidiasis was developed to allow the monitoring of the infection and the establishment of the aPDT treatment. Six-week-old female mice were immunosuppressed and inoculated with C. albicans to induce oral candidiasis. PDZ-mediated aPDT and nystatin treatment were carried out for 5 consecutive days with one application per day. The macroscopic evaluation of oral lesions was performed. After each treatment, the tongue was swabbed to recover C. albicans cells. Viable colonies were quantified and the number of CFU/ml determined. The animals were sacrificed 24 hours and 7 days after treatment and the tongues were surgically removed for histological analysis and analysis of inflammatory cytokines expression (IL-1, TNF-α and IL-6) by RT-qPCR. Data were analyzed by two-way ANOVA. PDZ-mediated aPDT was as effective as Nystatin (NYS group) in the inactivation of C. albicans, reducing 3 and 3.2 logs₁₀ respectively, 24 h after treatment (p<0.05). Animals underwent PDZ-mediated aPDT showed complete remission of oral lesions, while animals treated with NYS presented partial remission of oral lesions in both periods assessed. Histological evaluation revealed mild inflammatory infiltrate in the groups treated with aPDT and NYS in both periods assessed. The aPDT induced the TNF-α expression when compared with the control (P-L-) (p<0.05), 24 h and 7 days after treatment. In summary, the murine model developed here was able to mimic the infection and PDZ-mediated aPDT was effective to treat mice with oral candidiasis.

Candida albicans biofilms exhibit unique characteristics and are highly resistant to antifungal agents. Antimicrobial photodynamic therapy (aPDT) is an alternative treatment limited to treating superficial infections due to the poor light penetration. In this manuscript, the antifungal properties of sonodynamic therapy (SDT) were assessed. SDT uses ultrasound instead of light, enabling the treatment of deeper infections. Planktonic cells and biofilms of C. albicans were treated with aPDT or SDT, in addition to combined aPDT/SDT, with cell survival determined using colony forming units. The total biomass and structural integrity of the biofilms were also investigated. The results demonstrated that while individual aPDT or SDT eradicated suspensions, they had little impact on biofilms. However, combined aPDT/SDT significantly reduced the viability and total biomass of biofilms. Microscopic images revealed that biofilms treated with aPDT/SDT were thinner and comprised mainly of dead cells. These results highlight the potential of combined aPDT/SDT for the inactivation of C. albicans biofilms.