Atividade antifúngica, in vitro, de extratos de cultura de Candida spp. contra Trichophyton mentagrophytes e Trichophyton rubrum
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Data
2019-06-25
Autores
Lemes, Thiago Henrique
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Universidade Estadual Paulista (Unesp)
Resumo
Onicomicoses são infecções de unhas causadas principalmente por fungos dermatófitos, seguidos de leveduras e fungos filamentosos não dermatófitos (FFNDs). Caracterizam-se por serem infecções persistentes, de terapêutica prolongada com altas taxas de recorrência, falhas no seu diagnóstico e tratamento podem causar danos irreversíveis à placa ungueal. Na prática clínica é comum o achado de dois ou mais organismos responsáveis pela etiologia de onicomicoses. Nestes eventos, as interações interespécies conduzem respostas fisiológicas dos microrganismos com produção de moléculas difusíveis, denominadas moléculas de quorum sensing (QSMs), fundamentais para a sobrevivência microbiana em ambientes competitivos. De fato, nos últimos anos, novas QSMs fúngicas têm sido estudadas e descritas como potenciais agentes antimicrobianos. O presente estudo avaliou a atividade antifúngica dos extratos obtidos de cultura de Candida albicans e C. parapsilosis contra linhagens de dermatófitos, tal como seu efeito sinérgico com fluconazol e toxicidade. As culturas foram submetidas à filtração em sistema fechado, seguido por extração líquido-líquido, utilizando acetato de etila. A atividade antifúngica, in vitro, foi avaliada por microdiluição, obtendo-se a Concentração Inibitória Mínima (CIM) de cada extrato contra linhagens clínicas de Trichophtyton rubrum e T. mentagrophytes, além dos efeitos associados com fluconazol, por ensaio Checkerboard. Para avaliação de toxicidade, utilizou-se modelo invertebrado de Galleria mellonella. Os extratos de C. albicans e C. parapsilosis apresentaram CIM entre 250-2000 µg/mL contra as linhagens de dermatófitos, com efeito potencializado quando associado ao fluconazol, confirmando sinergismo. Os extratos apresentaram baixa toxicidade nas concentrações inibitórias mínimas. Futuramente, o isolamento e identificação dos compostos dos extratos possibilitarão novas abordagens terapêuticas no controle de infecções fúngicas.
Onychomycosis are nail infections caused primarily by dermatophyte fungi, followed by yeasts and non-dermatophyte filamentous fungi. They are characterized by being persistent infections, by the prolonged therapy with high recurrence episodes, failures in the diagnosis and treatment; wich can cause irreversible damage to the nail plate. In clinical practice, it is common for two or more organisms to be involved with onychomycosis. The interspecies interactions in infections of mixed etiology are mediated by small diffusible molecules called quorum sensing molecules (QSMs) and are fundamental for the survival of these microorganisms in competitive environments. In recent years, new fungal QSMs have been studied and described as potential antimicrobial agents. The present study evaluated the antifungal activity of the extracts obtained from the culture of Candida albicans and C. parapsilosis against strains of dermatophytes. To obtain the fungal extracts, the cultures were subjected to closed-loop filtration, followed by liquid-liquid extraction using ethyl acetate. The Minimal Inhibitory Concentration (MIC) of each extract was evaluated by the microdilution technique against clinical strains of Trichophtyton rubrum and T. mentagrophytes and in association with fluconazole, by the Checkerboard assay. To evaluate the toxicity of the extracts, an invertebrate model of Galleria mellonella was used. The extracts of C. albicans and C. parapsilosis showed MICs ranging from 250 to 2000 μg/mL. When associated with fluconazole, they expressed results showing a predominantly synergistic effect in all the evaluated combinations. Toxicity assays with G. mellonella demonstrated low toxicity of the extracts. In the future, the isolation and identification of the extract compounds will allow new therapeutic approaches in the control of fungal infections.
Onychomycosis are nail infections caused primarily by dermatophyte fungi, followed by yeasts and non-dermatophyte filamentous fungi. They are characterized by being persistent infections, by the prolonged therapy with high recurrence episodes, failures in the diagnosis and treatment; wich can cause irreversible damage to the nail plate. In clinical practice, it is common for two or more organisms to be involved with onychomycosis. The interspecies interactions in infections of mixed etiology are mediated by small diffusible molecules called quorum sensing molecules (QSMs) and are fundamental for the survival of these microorganisms in competitive environments. In recent years, new fungal QSMs have been studied and described as potential antimicrobial agents. The present study evaluated the antifungal activity of the extracts obtained from the culture of Candida albicans and C. parapsilosis against strains of dermatophytes. To obtain the fungal extracts, the cultures were subjected to closed-loop filtration, followed by liquid-liquid extraction using ethyl acetate. The Minimal Inhibitory Concentration (MIC) of each extract was evaluated by the microdilution technique against clinical strains of Trichophtyton rubrum and T. mentagrophytes and in association with fluconazole, by the Checkerboard assay. To evaluate the toxicity of the extracts, an invertebrate model of Galleria mellonella was used. The extracts of C. albicans and C. parapsilosis showed MICs ranging from 250 to 2000 μg/mL. When associated with fluconazole, they expressed results showing a predominantly synergistic effect in all the evaluated combinations. Toxicity assays with G. mellonella demonstrated low toxicity of the extracts. In the future, the isolation and identification of the extract compounds will allow new therapeutic approaches in the control of fungal infections.
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Palavras-chave
Micologia médica, Quorum sensing, Dermatófitos, Candida, Agentes antimicrobianos, Medical mycology, Dermatophytes, Antimicrobial agents