Phenotypic characterization of Trichophyton rubrum isolates from two geographic locations in Brazil

To characterize possible Trichophyton rubrum phenotypes, which circulate in two Brazilian localities, we tested 53 isolates of this dermatophyte for their ability to assimilate several carbon sources, for keratinase, proteinase, phospholipase, lipase and desoxiribonuclease (DNase) secretions, and for their susceptibility to the antifungals fluconazole, ketoconazole and itraconazole. For each method, the isolates were submitted to similarity analysis and the methods were evaluated for their discriminatory indexes. None of the isolates were capable of assimilating arabinose, dulcitol, lactose, melibiose, ribose and xylose, while all of the isolates assimilated maltose, sucrose and sorbitol. However, adonitol, cellobiose, dextrin, erythritol, fructose, galactose, inulin, mannitol, mannose, raffinose, rhamnose and trehalose were assimilated by some isolates but not by others. All isolates secreted keratinase and DNase, while none secreted phospholipase. Proteinase and lipase were secreted only by some isolates. All but four isolates were resistant to fluconazole, most of them were sensitive to ketoconazole and all were sensitive to itraconazole. Carbohydrate assimilation was the method that presented the highest discriminatory index, and also the method that displayed the largest number of biotypes. Taken together, these data suggest that significant phenotypic variations exist among T. rubrum isolates. They seem to occur independently from their geographic origins.