Morphological changes of the dermatophyteTrichophyton rubrumafter photodynamic treatment: a scanning electron microscopy study

Abstract

Treatment strategies for superficial mycosis caused by the dermatophyte Trichophyton rubrum consist of the use of topical or oral antifungal preparations. We have recently discovered that T. rubrum is susceptible to photodynamic treatment (PDT), with 5,10,15-tris(4-methylpyridinium)-20-phenyl-[21H,23H]-porphine trichloride (Sylsens B) as a photosensitizer. The susceptibility appeared to depend on the fungal growth stage, with PDT efficacy higher with microconidia when compared to mycelia. The aim of this study was to investigate, with the use of scanning electron microscopy, the morphological changes caused by a lethal PDT dose to T. rubrum when grown on isolated human stratum corneum. Corresponding dark treatment and light treatment without photosensitizer were used as controls. A sub-lethal PDT dose was also included in this investigation The morphologic changes were followed at various time points after the treatment of different fungal growth stages. Normal fungal growth was characterized by a fiber-like appearance of the surface of the hyphae and microconidia with the exception of the hyphal tips in full mycelia and the microconidia shortly after attachment to the stratum corneum. Here, densely packed globular structures were observed. The light dose (108 J/cm2) in the absence of Sylsens B, or the application of the photosensitizer in the absence of light, caused reversible fungal wall deformations and bulge formation. However, after a lethal PDT, a sequence of severe disruptions and deformations of both microconidia and the mycelium were observed leading to extrusion of cell material and emptied fungal elements. In case of a non-lethal PDT, fungal re-growth started on the remnants of the treated mycelium.

Mechanical Properties of Healthy and ex vivo Onychomycosis Nails and the Influence of a Porphyrin-propylene Glycol Antifungal Formulation

“…4A). Notice that our previous scanning electron microscope (SEM) study already illustrated dermatophytic morphology and dimension characteristics on human skin [17]. In this study we also noticed filamentous structures with widths of approximately 2-3 µm and rough, fibrelike surfaces.…”

“…4A). This flattening of fungal filaments resulting from applied antifungal PDT formulations was also noticed in previous SEM research [17]. Results of the post-treatment image roughness calculations are also given in Table 2.…”

Isolamento, caracterização e avaliação da atividade fotossensibilizadora de cumarinas e furanocumarinas extraídas de espécies de Citrus

“…O uso do tratamento fotodinâmico para matar estruturas fúngicas, como conídios, ascósporos e micélio, e para o tratamento de micoses é uma aplicação recente e promissora da técnica (De MENEZES 2014a,b;SCHITMAKER, 2003;SMIJS et al, 2004;SMIJS et al, 2007;SMIJS et al, 2008;SMIJS et al, 2009;GONZALES et al, 2010;PAVEL, 2011 (BARROS et al, 2010;De MENEZES et al, 2015). Conídios e esporos diferem de células metabolicamente ativas em relação a características bioquímicas (composição química das diferentes estruturas), fisiológicas (taxa metabólica, resposta ao estresse e expressão de mecanismos de adaptação e defesa) e estruturais (organização de estruturas intracelulares e espessura de parede), que podem influenciar o processo fotodinâmico (GONZALES et al, 2010;BARROS et al, 2010 (De SOUZA et al, 2006;DONNELLY;McCARRON;TUNNEY, 2008;BERNAL et al, 2011;De MENEZES et al, 2014b).…”

Efeito da inativação fotodinâmica com fotossensibilizadores fenotiazínicos em microconídios não germinados e germinados dos fungos Fusarium oxysporum, Fusarium moniliforme e Fusarium solani

“…Por meio do processo de cruzamento inter-sistemas, a molécula do FS passa do estado S 1 para o estado excitado tripleto (T 1 ), caracterizado pelo tempo de vida muito maior do que o estado S 1 . O estado tripleto pode reagir por meio de dois processos, conhecidos por fotoprocessos do Tipo I e do Tipo II, que requerem oxigênio molecular para que ocorram as reações (Hamblin et al, 2002, Donnelly, McCarron e Tunney, 2008 (Bilski et al, 1993;Ma e Jiang, 2001 pode levar a célula à morte, por consequência de dano oxidativo em várias biomoléculas (Sharman, Allen e van Lier, 2000;Bergamini et al, 2004;Plaetzer et al, 2009 (Halliwell, 1984a,b;Halliwell e Gutteridge, 1984;Plaetzer et al, 2009 (Halliwell, 1984a;Bergamini et al, 2004 (Smijs et al, 2008).…”

“…A microscopia confocal tem sido utilizada para determinar a captação e a localização intracelular de FS (So et al, 2010. Tanto a microscopia eletrônica de transmissão quanto a de varredura foram utilizadas para determinar os danos da IF no núcleo e na parede celular, respectivamente (So et al, 2010;Oriel e Nitzan, 2012;Smijs et al, 2008). Análises por citometria de fluxo foram utilizadas para avaliar danos na membrana, no material genético e 8 _________________________________________________________________________Introdução para avaliar o estresse oxidativo induzido pela IF (So et al, 2010).…”