Enhanced 5-aminolevulinic acid photodynamic therapy with potassium iodide for sporotrichosis: in vitro optimization and a proof-of-concept clinical case

Sporotrichosis, a chronic fungal infection caused by pathogenic Sporothrix species, involves therapeutic challenges due to the toxicity of conventional antifungals. This study investigated the enhancement of 5-aminolevulinic acid-based photodynamic therapy (ALA-PDT) with potassium iodide (KI) through in vitro and a proof-of-concept clinical case. In vitro testing on S. globosa conidia involved preincubation with 100 mM KI followed by ALA-PDT using 0.6 M ALA and 108 J/cm 2 red light irradiation. The efficacy of this combined approach was systematically compared with that of administering KI after ALA-PDT and that of using ALA-PDT alone. In the clinical setting, a patient with lymphocutaneous sporotrichosis and a history of itraconazole-induced liver injury underwent three sessions of KI-enhanced ALA-PDT using 0.7 M ALA (10%) and 100 J/cm 2 irradiation. Preincubation with 100 mM KI significantly enhanced the fungicidal effect of ALA-PDT against S. globosa conidia, resulting in a substantially reduced conidial survival rate compared to either administering KI after ALA-PDT or using ALA-PDT alone. Clinically, the patient treated with KI-enhanced ALA-PDT showed complete resolution of skin lesions and no recurrence during the 1-year follow-up period. This study evaluates a KI-enhanced ALA-PDT regimen in a patient with sporotrichosis, providing preliminary evidence that this approach may serve as a promising therapeutic option for patients intolerant to conventional antifungal therapy.