Use of a small cationic chlorin for antimicrobial Photodynamic Therapy in clinical isolates from patients with DFIs

Diabetic foot infections (DFI) are a significant complication of diabetes mellitus and the principal cause of lower limb amputations. Antimicrobial photodynamic therapy (aPDT) offers a promising alternative for treating these infections. The efficacy of aPDT using a novel photosensitizer, IC-H-Me 2+ , was tested against biofilms formed by clinical isolates from patients with DFI. Treatment with IC-H-Me 2+ alone and in combination with potassium iodide was tested. aPDT was performed using a 660 nm LED with a 5 J/cm 2 light dose. The fourteen clinical isolates produced different levels of biofilm after the same incubation period. All the biofilms showed more than 3 logs of colony forming units (CFU) reduction when treated with 1µM IC-H-Me 2+ and light, and most of them were completely eradicated when aPDT was potentiated by the addition of 50 mM KI. aPDT, particularly when combined with potassium iodide, could be an effective strategy for treatment of DFIs.