Household LED Light-Mediated Photodynamic Therapy for Effective Inhibition of Multidrug-Resistant Staphylococcus aureus

This study investigates the efficacy of toluidine blue O (TBO) and curcumin as photosensitizers for photodynamic therapy (PDT) against Staphylococcus aureus using a household LED bulb as the light source. Antibacterial and anti-biofilm activities were evaluated via colony-forming unit (CFU) and Congo red assays, while reactive oxygen species (ROS) generation was quantified using DCFH-DA dye. Confocal laser scanning microscopy (CLSM) was employed to assess live/dead bacterial cell ratios, and an in vivo skin abrasion model in Wistar rats was used to validate therapeutic outcomes. The CFU assay revealed substantial bacterial reductions, achieving 4.85 log₁₀ CFU/ml at 10 minutes for TBO and 2.81 log₁₀ CFU/ml at 15 minutes for curcumin. Extracellular polymeric substance (EPS) production decreased by 96.22% with TBO and 48.98% with curcumin, accompanied by enhanced ROS generation. CLSM confirmed a higher dead-to-live cell ratio following PDT. In vivo results, supported by histopathological examination and cytokine expression profiling, further demonstrated the effectiveness of TBO- and curcumin-mediated PDT under LED light. Overall, these findings highlight the potential of readily available household LED bulbs as an accessible and efficient light source for PDT, offering robust antimicrobial activity against S. aureus .