In Vitro Effect of Photodynamic Therapy with Different Lights and Combined or Uncombined with Chlorhexidine on Candida spp.

Abstract

Candidiasis is very common and complicated to treat in some cases due to increased resistance to antifungals. Antimicrobial photodynamic therapy (aPDT) is a promising alternative treatment. It is based on the principle that light of a specific wavelength activates a photosensitizer molecule resulting in the generation of reactive oxygen species that are able to kill pathogens. The aim here is the in vitro photoinactivation of three strains of Candida spp., Candida albicans ATCC 10231, Candida parapsilosis ATCC 22019 and Candida krusei ATCC 6258, using aPDT with different sources of irradiation and the photosensitizer methylene blue (MB), alone or in combination with chlorhexidine (CHX). Irradiation was carried out at a fluence of 18 J/cm2 with a light-emitting diode (LED) lamp emitting in red (625 nm) or a white metal halide lamp (WMH) that emits at broad-spectrum white light (420–700 nm). After the photodynamic treatment, the antimicrobial effect is evaluated by counting colony forming units (CFU). MB-aPDT produces a 6 log10 reduction in the number of CFU/100 μL of Candida spp., and the combination with CHX enhances the effect of photoinactivation (effect achieved with lower concentration of MB). Both lamps have similar efficiencies, but the WMH lamp is slightly more efficient. This work opens the doors to a possible clinical application of the combination for resistant or persistent forms of Candida infections.

Antimicrobial Activity of Methylene Blue Associated with Photodynamic Therapy: In Vitro Study in Multi-Species Oral Biofilm

“…In different types of infections, it has been shown that photodynamic therapy is strain- and photosensitizer-dependent [ 56 ] and that it has a cumulative effect with the mixture of other antimicrobials [ 57 ]. A factor that must be taken into account and that can increase the antimicrobial activity of the photosensitizer is the incubation/pre-irradiation time, since this could increase the joint effect of the MB + LED [ 58 ].…”

Antibacterial Activity of Endodontic Gutta-Percha—A Systematic Review

“…Furthermore, chlorhexidine exhibits biocidal activity against Gram-positive bacteria, and, if the minimum inhibitory concentration (MIC) is maintained, it can also inhibit Gram-negative bacteria. Additionally, chlorhexidine remains active against DNA and RNA viruses and yeast, including Candida albicans [48][49][50][51][52][53].…”

Clinical applications of antimicrobial photodynamic therapy in dentistry

“…In addition, these medications have a limited range of action, and they can be toxic ( Morio et al, 2017 ; Rodríguez-Cerdeira et al, 2021 ). Thus, other therapeutic approaches have been investigated against oral fungal infections in recent years, e.g., using oregano oil, tea tree oil, ozone therapy, nanoparticles, and light therapy ( Ninomiya et al, 2013 ; Szweda et al, 2015 ; Maciel et al, 2016 ; Bhat et al, 2018 ; Monzillo et al, 2020 ; Pérez-Laguna et al, 2021 ). Many studies have introduced aPDT as a promising approach instead of the conventional antifungal treatments in managing oral candidiasis and denture stomatitis ( Kato et al, 2013 ; Azizi et al, 2016 ; Janeth Rimachi Hidalgo et al, 2019 ; Alves et al, 2020 ).…”