A novel ex vivo skin model to study the susceptibility of the dermatophyte Trichophyton rubrum to photodynamic treatment in different growth phases

• Published in: Journal of antimicrobial chemotherapy 2007-03, Vol.59 (3), p.433-440
• Main Authors: Smijs, Threes G. M., Bouwstra, Joke A., Schuitmaker, Hans J., Talebi, M., Pavel, Stan
• Format: Article
• Language: English
• Subjects: Antibiotics. Antiinfectious agents. Antiparasitic agents; Biological and medical sciences; Culture Media; Deuteroporphyrins - pharmacology; Diseases of the skin. Cosmetics; Epidermis - microbiology; ex vivo model; Fungal infections; Human mycoses; Humans; Hydrogen-Ion Concentration; Infectious diseases; Light; Medical sciences; Medical treatment; microconidia; Microscopy, Fluorescence; Mycoses; Mycoses of the skin; Pharmacology. Drug treatments; Photochemotherapy; porphyrins; Porphyrins - analysis; Porphyrins - pharmacology; Pyridinium Compounds - analysis; Pyridinium Compounds - pharmacology; Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects); Skin diseases; stratum corneum; Substance abuse treatment; tinea; Trichophyton - drug effects; Trichophyton rubrum
• ISSN: 0305-7453; 1460-2091
• DOI: 10.1093/jac/dkl490

Background Dermatophytes are fungi that can cause infections of skin, hair and nails because of their ability to feed on keratin. Superficial mycoses are among the most prevalent infectious diseases worldwide. Two important restrictions of current therapeutic options are the recurrence of the infection and prolonged treatment. This is especially true for infections caused by Trichophyton rubrum, a widely distributed dermatophyte. The application of photosensitizers for treatment of fungal infections is, within the field of photodynamic treatment (PDT), relatively new. Recently, we demonstrated that the porphyrins 5,10,15-tris(4-methylpyridinium)-20-phenyl-[21H,23H]-porphine trichloride (Sylsens B) and deuteroporphyrin monomethylester (DP mme) were excellent photosensitizers towards T. rubrum when using red light. Objectives and methods To evaluate the photodynamic effectiveness of the porphyrins in a situation that mimics the clinical situation, we developed an ex vivo model using human stratum corneum. This model offers the possibility of applying PDT at different time points during the germination and subsequent development of T. rubrum microconidia. The model was used for two different incubation media, Dulbecco's modified Eagle medium (DMEM) and distilled water. Results and conclusions We demonstrated that the PDT susceptibility of T. rubrum depended on the time of PDT application after spore inoculation. A decrease in susceptibility was observed with increasing time of PDT application for both photosensitizers in DMEM. Changing the incubation medium to distilled water resulted in an increased fungicidal effect for Sylsens B and in a decreased effect for DP mme. We conclude that T. rubrum is susceptible to PDT in a situation that mimics the clinical situation. The fungicidal effect of PDT on fungal spores is of particular importance.