The rise of multi-drug-resistant bacteria and fungi has led to search for novel antimicrobial therapies to treat infections. Photodynamic inactivation (PDI) is a potential candidate; it uses the combination of a photosensitizer (PS) with visible light to produce reactive oxygen species that lead to cell death. There was no evidence that repeated PDI could induce resistance of the microbes against this treatment. To increase the efficacy of PDI, PS could be encapsulated either in liposomes or micelles to prevent aggregation in aqueous medium. Evidences indicate that PS entrapped in micelle exert similar or better PDI efficacy than that of liposome, which indicates that this formulation may be useful for the treatment of local infections. Our studies also showed that chitosan can potentiate the PDI efficacy against bacteria and yeasts in planktonic cells or biofilms. After PDI application, the addition of chitosan can greatly augment the killing of microbes. Besides, using LED red light, we showed that topical 5-aminolevulinic acid (ALA) photodynamic therapy (PDT) was a effective treatment of verruca vulgaris. It cured the warts mostly on the feet and hands with a complete cure rate more than 90%. The advantages of ALA-PDT were simplicity and leaving no scar, although mild to moderate pain occurred during illumination. In conclusion, antimicrobial PDT has been applied extensively and not only plays an important role in preventing the emergences of multi-drugs-resistant microbes, it also can cure local infections of drug-resistant microbes.
- photodynamic inactivation
- drug resistance