Molecular characterization of selected dermatophytes and their identification by electrophoretic mutation scanning

Dermatophytes are fungi that can be contagious and cause infections in the keratinized skin of mammals, including humans. The etiological diagnosis of dermatophytosis relies on a combination of in vitro-culture and microscopic methods. Effective molecular tools could overcome the limitations of conventional methods of identification. In the present study, following phenetic identification as M. canis, M. fulvum, M. gypseum, T mentagrophytes and T terrestre, we genetically characterized key dermatophytes, employing the sequences of the first and second internal transcribed spacers of nuclear ribosomal DNA as well as part of the chitin synthase-1 gene, and assessed the utility of these DNA regions (based on levels of nucleotide variation within and among species/taxa) as markers for the classification of species and genotypes. Employing partial chitin synthase-1 gene as the marker, we also established a PCR-coupled SSCP approach as a diagnostic/analytical mutation-scanning tool. This tool should facilitate fundamental investigations of the ecology, epidemiology and population genetics of dermatophytes and, importantly, should assist in allowing a more rapid diagnosis of dermatophytoses in humans and other animals, thus overcoming the significant delays in targeted chemotherapy following diagnosis using conventional methods. (Nucleotide sequence data reported in this paper are available in the EMBL, GenBank and DDJB datadases under accession numbers FJ897707-FJ897713 (ITS-1), FJ897714-FJ897720 (ITS-2) and FJ897700-FJ897706 (pchs-1)).