In vitro photodynamic inactivation of Candida albicans by phenothiazine dye (new methylene blue) and Indocyanine green (EmunDo®).

BACKGROUND

The application of a new generation of photosensitizers to increase the efficacy of antifungal photodynamic therapy (aPDT) is an important aspect of PDT. Thus, this in vitro study is aimed to evaluate the antifungal efficacy of the photo-elimination of Candida albicans with photothermal and antifungal photodynamic therapy.

METHOD AND MATERIAL

aPDT with new methylene blue and photothermal therapy with EmunDo® were applied to a fungal suspension, which was then subcultured in Sabouraud dextrose agar (SDA). The C. albicans colonies were counted and are expressed as colony-forming unit per milliliter (CFU/ml).

RESULTS

aPDT with either EmunDo® or new methylene blue (NMB) considerably diminished the viability of inoculated C. albicans (P<0.001) by log reduction of 1.9 and 3.37, respectively, compared with the control group respectively, compared with the control group. The antifungal potency or dark toxicity of the two photosensitizers alone did not significantly differ (P=0.70). The same trend was observed for the light sources (λ: 810nm vs. λ: 630nm), which also did not significantly differ (P=0.78).

CONCLUSION

The photo-elimination of C. albicans with either new methylene blue or EmunDo® as a photosensitizer can reduce the viability of fungal cells. Although the result of this study is encouraging, further investigations are warranted to determine clear protocols for the reliable and safe application of this method in clinical practice.