Treatment of oral candidiasis with methylene blue-mediated photodynamic therapy in an immunodeficient murine model.
OBJECTIVE
The purpose of this study was to evaluate the efficacy of using methylene blue (MB)-mediated photodynamic therapy to treat oral candidiasis in an immunosuppressed murine model, mimicking what is found in human patients.


METHODS
Seventy-five experimental mice with severe combined immunodeficiency disease were inoculated orally with Candida albicans by swab 3 times a week for a 4-week period. On treatment day, mice were cultured for baseline fungal growth and received a topical oral cavity administration of 0.05 mL MB solution at one of the following concentrations: 250, 275, 300, 350, 400, 450, or 500 microgram/mL. After 10 minutes the mice were recultured and underwent light activation with 664 nm of diode laser light with a cylindrical diffuser. After photodynamic therapy the mice were cultured again for colony-forming units per milliliter and then killed, their tissue harvested for histopathology.


CONCLUSIONS
The results indicate an MB dose-dependent effect. Concentrations from 250 to 400 microgram/mL reduced fungal growth but did not eliminate Candida albicans. MB concentrations of 450 and 500 microgram/mL totally eradicated Candida albicans from the oral cavity, resulting in reductions from 2.5 log(10) and 2.74 log(10) to 0, respectively. These results suggest that MB-mediated photodynamic therapy can potentially be used to treat oral candidiasis in immunodeficient patients.
Teichert
M C
MC
Advanced Photodynamic Technologies, Inc, Minneapolis, MN 55345, USA.
Jones
J W
JW
Usacheva
M N
MN
Biel
M A
MA
D000818:Animals; D000935:Antifungal Agents / Q000494:pharmacology; D001393:Azoles / Q000494:pharmacology; D002176:Candida albicans / Q000187:drug effects; D002180:Candidiasis, Oral / Q000188:drug therapy* / Q000382:microbiology; D015169:Colony Count, Microbial; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D025141:Drug Resistance, Fungal; D008751:Methylene Blue / Q000008:administration & dosage* / Q000627:therapeutic use; D051379:Mice; D008819:Mice, Nude; D016513:Mice, SCID; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000008:administration & dosage* / Q000627:therapeutic use
D000935:Antifungal Agents; D001393:Azoles; D017319:Photosensitizing Agents; D008751:Methylene Blue