Análise fenotípica e genotípica de isolados de Trichophyton rubrum de pacientes com dermatofitoses

Abstract

Dermatophytoses or ringworms are fungal infections of the keratinized tissues of man and animals, caused by a group of specific fungi, called dermatophytes. Among the dermatophyte species, Trichophyton rubrum is one of the most important affecting adult individuals, and tends to produce infections of an evolutionary course of the chronic type, with disseminated, persistent and recurrent lesions. The laboratory diagnosis of dermatophytoses in routine is based on the phenotypic characteristics of the fungal strains isolated from the lesions in specific culture media, for this it is necessary to study the macro and micromorphology aspects of the colonies and, biochemical tests when necessary. However different T. rubrum isolates may show variability intheir phenotypic characteristics, and these may be related to genetic differences. The purpose of this study was to describe different phenotypes and to evaluate the possible existence of genotypic variability of T. rubrum isolates from pacients with dermatophytoses treated at a referral center in tropical dermatology in the city of Manaus-AM. For this, the method of random amplification of polymorphic DNA was used with use of the primer 1: 5-GGTGCGGGAA-3. From the phenotyping of 55 isolates of T. rubrum, 07 phenotypes were evidenced. The analysis of T.rubrum isolates using the RAPD with primer 1 allowed the discrimination of 10 distinct genotypic profiles, distributed in three groups, with the majority of isolates belonging to the same genetic group, group I, with 85% similarity. No association were found between the different phenotypes and genotypes, or between these and the clinical data of the patients. Despite the proven potencial of the RAPD technique for studies on the genetic variability of T. rubrum, new methods that make it possible a correlation between the different genotypes and the clinical and epidemiological aspects of dermatophytoses still need to be evaluated or developed.