Photodynamic Eradication of <i>Trichophyton rubrum</i> and <i>Candida albicans</i>

• Main Authors: Anton Valkov, Michael Zinigrad, Marina Nisnevitch
• Format: Article
• Language: English
• Published: MDPI AG 2021-02-01
• Series: Pathogens
• Subjects: photodynamic treatment; rose Bengal; malachite green; methylene blue; Trichophyton rubrum; <i>Candida albicans</i>
• Online Access: https://www.mdpi.com/2076-0817/10/3/263

Conventional methods of onychomycosis treatment are ineffective in some cases because the cure of onychomycosis very often depends on the patient’s individual response to the treatment; therefore, there is a crucial need to research and develop new methods of onychomycosis therapy. One of the most innovative treatments is photodynamic therapy (PDT) using photosensitizers (PSs). However, effective treatment depends on the correct choice of photosensitizer and substances that improve the characteristics of the final formulation. The aim of our work was to find an effective formulation for the treatment of onychomycosis. To achieve this goal, we tested the effect of three types of PSs, rose Bengal (RB), malachite green oxalate (MGO), and methylene blue (MB), on <i>Candida albicans</i>. The most effective PS was RB, and so the study was continued with <i>Trichophyton rubrum</i>. Additional comparative studies were carried out on substances included in the formulation (urea and thiourea), focusing on their antifungal activity, which can improve penetration through the nail plate. The composition of the formulation that achieved 100% eradication of <i>Trichophyton rubrum</i> under our conditions consisted of 150 μM RB, 5% urea, and 0.5% thiourea in glycerol/water (70/30%, <i>w</i>/<i>w</i>) solution. A white luminescent lamp was used as a light source (1.9 ± 0.1 mW cm⁻²). Stability of the formulation was checked. The selected formulation shows potential for future simplification and acceleration of PDT treatment of onychomycosis.