Phototoxic action of light emitting diode in the in vitro viability of Trichophyton rubrum

Abstract

BACKGROUND -Trichophyton rubrum is the most common agent of superficial mycosis of the skin and nails causing long lasting infections and high recurrence rates. Current treatment drawbacks involve topical medications not being able to reach the nail bed at therapeutic concentrations, systemic antifungal drugs failing to eradicate the fungus before the nails are renewed, severe side effects and selection of resistant fungal isolates. Photodynamic therapy (PDT) has been a promising alternative to conventional treatments. OBJECTIVES: This study evaluated the in vitro effectiveness of toluidine blue O (TBO) irradiated by Light emitting diode (LED) in the reduction of T. rubrum viability. METHODS: The fungal inoculums' was prepared and exposed to different TBO concentrations and energy densities of Light emitting diode for evaluate the T. rubrum sensibility to PDT and production effect fungicidal after photodynamic treatment. In addition, the profiles of the area and volume of the irradiated fungal suspensions were also investigated. RESULTS: A small reduction, in vitro, of fungal cells was observed after exposition to 100 μM toluidine blue O irradiated by 18 J/cm 2 Light emitting diode. Fungicidal effect occurred after 25 μM toluidine blue O irradiation by Light emitting diode with energy density of 72 J/cm 2 . The analysis showed that the area and volume irradiated by the Light emitting diode were 52.2 mm² and 413.70 mm³, respectively. CONCLUSIONS: The results allowed to conclude that Photodynamic therapy using Light emitting diode under these experimental conditions is a possible alternative approach to inhibit in vitro T. rubrum and may be a promising new treatment for dermatophytosis caused by this fungus. Keywords: Antifungal agents; Onychomycosis; Photochemotherapy Resumo: FUNDAMENTOS -Trichophyton rubrum é o agente mais comum das micoses superficiais de pele e unhas causando infecções de longa duração e altas taxas de recidiva. As desvantagens do tratamento atual envolvem medicações tópicas as quais não são capazes de alcançar o leito ungueal em concentrações terapêuticas, antifúngicos sistêmicos que não erradicam o fungo antes das unhas serem renovadas, efeitos colaterais graves e seleção de isolados fúngicos resistentes. A terapia fotodinâmica tem sido uma alternativa promissora aos tratamentos convencionais. OBJETIVOS -Este estudo avaliou a eficácia, in vitro, de azul de orto-toluidina irradiado por diodo emissor de luz na redução da viabilidade de T. rubrum. MÉTODOS: O inóculo fúngico foi preparado e exposto a diferentes concentrações de azul de orto-toluidina e densidades de energia do diodo emissor de luz, para avaliar a sensibilidade de T. rubrum e o efeito fungicida, após terapia fotodinâmica. Além disso, os perfis da área e volume das suspensões fúngicas irradiados também foram investigados. RESULTADOS: Uma pequena redução, in vitro, de células fúngicas foi observada após a exposição a 100 mM azul de orto-toluidina irradiados por diodo emissor de luz a 18 J/cm 2 . Efeito fungicida ocorreu a...

An in vitro study of the photodynamic effect of rose bengal on trichophyton rubrum

“…Photosensitizers, such as methylene blue and toluidine blue, have been shown to be a vital adjunct when using visible light to treat bacterial and fungal infections [19][20][21][22]. They are chosen on the basis of their charge, ability to be non-toxic without illumination (dark toxicity) and the ability to become genotoxic or mutagenic following irradiation [23].…”

Novel light therapies in treatment of onychomycosis

“…W warunkach in vitro sprawdzano również skuteczność innych związków o działaniu fotouwraż-liwiającym, takich jak błękit toluidynowy O (TBO), w połączeniu z naświetlaniem za pomocą lampy LED [43]. Ponadto w badaniu klinicznym stwierdzono skuteczność terapii fotodynamicznej z mieszaniną błękitu toluidynowego oraz błękitu metylenowego, dzięki której uzyskano całkowite ustąpienie zmian u prawie połowy badanych (28 spośród 62), natomiast znaczną poprawę u kolejnych, ale u niektórych nie osiągnięto poprawy w ogóle [44].…”

Endonyx toenail onychomycosis caused by Trichophyton rubrum: treatment with photodynamic therapy based on methylene blue dye

“…6 T. rubrum was believed to be exclusively ectothrix but is currently known to be either ectothrix or endothrix. 7,8 …”

“…3 Previous clinical trials and in vitro studies have demonstrated the effectiveness of PDT, but indicated the need for adequate energy density and concentration of the photosensitive dye. 3,8 The increased energy density used in this study might reduce the number of sessions and the treatment duration due to the increased PDT fungicidal activity. 8 The use of macrocyclic molecules with fewer sessions (3 on average), because of the high cost, has resulted in a clinical cure rate lower than that of azole drugs, probably due to the inadequate number of sessions.…”

“…3,8 The increased energy density used in this study might reduce the number of sessions and the treatment duration due to the increased PDT fungicidal activity. 8 The use of macrocyclic molecules with fewer sessions (3 on average), because of the high cost, has resulted in a clinical cure rate lower than that of azole drugs, probably due to the inadequate number of sessions. 9,10 …”