Avaliação de métodos de extração de DNA e de identificação de dermatófitos por análise de PCR-RFLP

Abstract

Dermatophytes comprise a group of filamentous fungi of great interest on public health because of their ability to parasitize keratinized tissues, such as skin, hair and nails, and for their wide distribution in the world. As a consequence of this parasitism, an infectious process of dermatophytosis is established, from which a variety of clinical manifestations can occur, affecting people of both genders and all age groups. Laboratory methods for mycological diagnosis do not always allow a clear an especific definition of the agent. In this study, different strategies for extraction of DNA, and molecular typing by PCR-RFLP, of seven dermatophyte species were assessed. Two target regions: ITS/rDNA and the topoisomerase II gene were evaluated, by testing three PCR protocols and three restriction enzymes (DdeI, HinfI, HaeIII). For the DNA extraction, the glass bead shaking technique for cell lysis, followed by Gustincich (1991) based mehod for DNA separation, demonstrated more advantages. Our results has demonstrated that the topoisomerase II gene is a suitable target region for identification of the seven major pathogenic dermatophyte fungal species, reinforcing previous studies, and pointed to a new PCR-RFLP protocol, which is based on a PCR of this gene using dPsD2 primer, followed by digestion of PCR products with HaeIII restriction enzyme.