Comparative evaluation of photodynamic therapy induced by two different photosensitizers in rat experimental candidiasis

Abstract

Background: Antimicrobial effi cacy of photodynamic therapy (PDT) depends on both the
photosensitizer (PS) and laser parameters. In the present study, antimicrobial effectiveness of PDT
with different concentrations of two PSs was compared.
Materials and Methods: In this study, we employed fi fty-nine 6-week-old male Wistar rats. All
except the negative and overall control groups were immunosuppressed and then orally inoculated
with a suspension of Candida albicans (9 × 108 CFU/ml). At 4 days after oral inoculation, swabbing
of tongue dorsum was performed to recover yeast from the tongue before treatment; on the next
day, PDT was carried out on tongue dorsums by use of different concentrations of methylene blue
(MB) or poly-L-lysine-chlorine (e6) conjugate (pL-ce6) as PS; followed by a 10 min diode laser
illumination at 660 nm (n = 6 each). Then, sampling was again performed. The difference between
yeast recovery before and after treatment was compared between the groups by one-way analysis
of variance test (α = 0.05). After sac rifi cing the animals, their tongues were surgically removed and
processed for histological evaluation of the presence of yeast and tissue reaction.
Results: PDT mediated by both PSs, regardless of the type and their concentration, resulted in a signifi cant
microbiological and histological reduction in C. albicans counts in comparison with positive control group
(P < 0.001). There was no difference in epithelial lesions and infl ammatory responses between groups.
Conclusion: PDT mediated MB or pL-ce6 is a promising approach for treatment of oral candidiasis.
Key Words: Candida albicans, methylene blue, photodynamic therapy, photosensitizer,
poly-L-lysine-chlorine (e6) conjugate