Abstract :
The objective of this study was to establish the phenotypical and molecular patterns of clinical isolates of Trichophyton tonsurans circulating in the state of Ceara, northeastern Brazil. For this purpose, 25 T. tonsurans strains isolated from independent cases of tinea capitis in children were phenotypically evaluated regarding their macro- and micro-morphological characteristics, vitamin requirements, urease production, and antifungal susceptibility. The molecular characterization was carried out with random amplified polymorphic DNA molecular markers and M13 fingerprinting. The presence of the genes CarbM14, Sub2, CER, URE, ASP, PBL, and LAC, which encode enzymes related to fungal virulence, was also evaluated. Finally, melanin production was assessed through specific staining. The data obtained demonstrated that these T. tonsurans strains have considerable phenotypical variation, although they showed a low degree of genetic polymorphism according to the markers used. The genes CarbM14, Sub2, CER, and URE were detected in all the analyzed strains. The gene LAC was also identified in all the strains, and melanin synthesis was phenotypically confirmed. The strains were susceptible to antifungals, especially itraconazole (GM = 0.06 [micro]g/mL) and ketoconazole (GM = 0.24 [micro]g/mL). Therefore, T. tonsurans strains can present great phenotypical heterogeneity, even in genetically similar isolates. Moreover, the presence of the LAC gene indicates the possible participation of melanin in the pathogenesis of these dermatophytes. Key words: Trichophyton tonsurans, phenotyping, genotyping, virulence factors. Les objectifs de la presente etude etaient de tracer le portrait phenotypique et moleculaire d'isolats cliniques de Trichophyton tonsurans qui circulent dans l'etat de Ceara, dans le nord-est du Bresil. Pour y parvenir, on a evalue le phenotype de 25 souches de T. tonsurans isolees de cas independants de teigne chez des enfants, en s'attardant a leurs caracteristiques macroet micromorphologiques, besoins vitaminiques, production d'urease et susceptibilite aux antifongiques. On a procede a leur caracterisation moleculaire au moyen d'un marquage moleculaire par RAPD et d'une prise d'empreintes par phage M13. La presence des genes CarbM14, Sub2, CER, URE, ASP, PBL et LAC, qui codent des enzymes liees a la virulence fongique, a egalement ete evaluee. Finalement, une coloration specifique a mesure la production de melanine. Les donnees obtenues montrent que ces souches de T. tonsurans font preuve d'une variabilite phenotypique considerable, meme s'ils demontrent un faible niveau de polymorphisme genetique d'apres les marqueurs employes. Les genes CarbM14, Sub2, CER et URE ont ete detectes chez toutes les souches analysees. Le gene LAC a egalement ete repere chez toutes les souches et la synthese de melanine a ete confirmee phenotypiquement. Les souches etaient susceptibles aux antifongiques, en particulier l'itraconazole (MG = 0.06 [micro]g/mL) et le ketoconazole (MG = 0.24 [micro]g/mL). Par consequent, les souches de T. tonsurans peuvent faire etalage d'une grande heterogeneite phenotypique, meme en presence d'isolats genetiquement semblables. En outre, la presence du gene LAC indique que la melanine pourrait participer a la pathogenese de ces dermatophytes. [Traduit par la Redaction] Mots-cles: Trichophyton tonsurans, phenotypage, genotypage, facteurs de virulence.