Susceptibilities of the dermatophytes Trichophyton mentagrophytes and T. rubrum microconidia to photodynamic antimicrobial chemotherapy with novel phenothiazinium photosensitizers and red light

• Published in: Journal of photochemistry and photobiology. B, Biology Biology, 2012-11, Vol.116, p.89-94
• Main Authors: Rodrigues, Gabriela B., Ferreira, Liana K.S., Wainwright, Mark, Braga, Gilberto U.L.
• Format: Article
• Language: English
• Subjects: Anti-Infective Agents - pharmacology; Arthrodermataceae - drug effects; Arthrodermataceae - radiation effects; Color; drug therapy; keratinophilic fungi; Light; methylene blue; Methylene blue derivatives; Microbial Sensitivity Tests; minimum inhibitory concentration; mycoses; Phenothiazines - pharmacology; Photoantimicrobial; photobiology; photochemistry; Photodynamic antimicrobial chemotherapy; photosensitizing agents; Photosensitizing Agents - pharmacology; red light; Spores, Fungal - drug effects; Spores, Fungal - radiation effects; toluidine blue; Trichophyton - drug effects; Trichophyton - radiation effects; Trichophyton mentagrophytes; Trichophyton rubrum
• ISSN: 1011-1344; 1873-2682
• DOI: 10.1016/j.jphotobiol.2012.08.010

► Dermatophytoses are among the most common and widespread infectious diseases worldwide. ► Photodynamic antimicrobial chemotherapy is a promising alternative to conventional chemotherapy. ► Development of PACT depends on identifying effective PS for the different pathogenic species. ► PACT with the new MB derivatives S137 and NMBN was more effective than with MB and TBO. ► Complete fungal killing was achieved for both species. Photodynamic antimicrobial chemotherapy (PACT) is a promising alternative to conventional chemotherapy that can be used to treat localized mycosis. The development of PACT depends on identifying effective and selective PS for the different pathogenic species. The in vitro susceptibilities of Trichophyton mentagrophytes and Trichophyton rubrum microconidia to PACT with methylene blue (MB), toluidine blue O (TBO), new methylene blue N (NMBN), and the novel pentacyclic phenothiazinium photosensitizer S137 were investigated. The efficacy of each PS was determined based on its minimal inhibitory concentration (MIC). Additionally, we evaluated the effect of PACT with NMBN and S137 on the survival of the microconidia of both species. S137 showed the lowest MIC. MIC for S137 was 2.5μM both for T. mentagrophytes and T. rubrum, when a light dose of 5Jcm−2 was used. PACT with NMBN (10μM and 20Jcm−2) resulted in a reduction of 4 logs in the survival of the T. rubrum and no survivor of T. mentagrophytes was observed. PACT with S137 at 1μM and 20Jcm−2 resulted in a reduction of approximately 3 logs in the survival of both species. When a S137 concentration of 10μM was used, no survivor was observed for both species at all light doses (5, 10 and 20Jcm−2).