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Updated: May 7, 2026
Rose Bengal-Mediated Photodynamic Therapy to Inhibit Candida albicans
Published on: March 24, 2022
Photodynamic inactivation of four Candida species induced by photogem(®)
Lívia Nordi Dovigo1, Ana Cláudia Pavarina, Daniela Garcia Ribeiro
1Department of Dental Materials and Prosthodontics, Araraquara Dental School, São Paulo State University Araraquara, SP Brasil.
Abstract:
This study evaluated the in vitro susceptibility of C. albicans, C. dubliniensis, C. tropicalis and C. krusei to photodynamic therapy (PDT) induced by Photogem(®)and light emitted diode (LED). Suspensions of each Candida strain were treated with three photosensitizer (PS) concentrations (10, 25 and 50 mg/L) and exposed to 18, 25.5 and 37.5 J/cm(2) LED light fluences (λ ~ 455 nm). Control suspensions were treated only with PS concentrations, only exposed to the LED light fluences or not exposed to LED light or PS. Sixteen experimental conditions were obtained and each condition was repeated three times. From each sample, serial dilutions were obtained and aliquots were plated on Sabouraud Dextrose Agar. After incubation of plates (37 °C for 48 hours), colonies were counted (cfu/mL) and the data were statistically analyzed by ANOVA and the Tukey test (α=0.05). Complete killing of C. albicans was observed after 18 J/cm(2) in association with 50 mg/L of PS. C. dubliniensis were inactivated after 18 J/cm(2) using 25 mg/L of PS. The inactivation of C. tropicalis was observed after photosensitization with 25 mg/L and subsequent illumination at 25.5 J/cm(2). For C. krusei, none of the associations between PS and light resulted in complete killing of this species. PDT proved to be effective for the inactivation of C. albicans, C. dubliniensis and C. tropicalis. In addition, reduction in the viability of C. krusei was achieved with some of the PS and light associations.
Insights
Photodynamic therapy (PDT) using Photogem® and LED light effectively inactivated Candida albicans, Candida dubliniensis, and Candida tropicalis in vitro. Some PDT combinations reduced Candida krusei viability, but did not achieve complete inactivation.
Area of Science:
- Mycology
- Photobiology
- Antimicrobial Therapy
Background:
- Candida species are significant opportunistic fungal pathogens.
- Antifungal resistance necessitates novel therapeutic strategies.
- Photodynamic therapy (PDT) shows promise as an antimicrobial approach.
Purpose of the Study:
- To evaluate the in vitro efficacy of photodynamic therapy (PDT) against common Candida species.
- To determine optimal photosensitizer (PS) concentrations and light fluences for Candida inactivation.
- To assess the susceptibility of Candida albicans, Candida dubliniensis, Candida tropicalis, and Candida krusei to PDT.
Main Methods:
- Candida species were exposed to varying concentrations of Photogem® photosensitizer (PS) and light-emitting diode (LED) light fluences.
- Experimental conditions included different PS concentrations (10, 25, 50 mg/L) and light fluences (18, 25.5, 37.5 J/cm²).
- Colony-forming units per milliliter (cfu/mL) were counted after incubation, and data were analyzed using ANOVA and Tukey's test.
Main Results:
- Complete inactivation of Candida albicans was achieved with 50 mg/L PS and 18 J/cm² light.
- Candida dubliniensis inactivation occurred with 25 mg/L PS and 18 J/cm² light.
- Candida tropicalis inactivation was observed with 25 mg/L PS and 25.5 J/cm² light; Candida krusei showed reduced viability but not complete inactivation.
Conclusions:
- Photodynamic therapy (PDT) is effective for in vitro inactivation of Candida albicans, Candida dubliniensis, and Candida tropicalis.
- PDT demonstrates potential as an alternative or adjunctive therapy against specific Candida infections.
- Candida krusei exhibits higher resistance to the tested PDT conditions compared to other Candida species evaluated.
