title: Molecular typing and antifungal susceptibility of Trichophyton rubrum isolates from patients with onychomycosis pre- and post-treatment.
abstract: Forty sequential isolates of Trichophyton rubrum were obtained from patients suffering from onychomycosis at two time points, before and after antifungal oral therapy. Strain differentiation by specific amplification of the two tandemly repeated elements (TRS-1 and TRS-2) of the ribosomal DNA of T. rubrum was performed. In addition, susceptibility tests were executed by the microdilution method with nine antifungal drugs: ketoconazole, itraconazole, fluconazole, miconazole, clotrimazole, isoconazole, griseofulvin, cyclopiroxolamine and terbinafine. The combination of TRS-1 with TRS-2 PCR amplification patterns configured 11 T. rubrum genotypes and the three most prevalent (genotypes 1-I, 5-I and 2-I) accounted for 67.5% of the isolates. Seven isolates (35%) obtained before antifungal oral therapy exhibited genotype 1-I compared to the 11 (55%) obtained after the treatment. Twelve patients exhibited different strains before and after the antifungal therapy. With respect to in vitro susceptibility testing, terbinafine was the most potent agent, followed by itraconazole, clotrimazole, isoconazole, miconazole, cyclopiroxolamine, ketoconazole, griseofulvin and fluconazole. Furthermore, an increase in the minimum inhibitory concentrations (MIC) were observed for most of the azole agents when testing isolates obtained post-treatment from four patients. This increase in MIC occurred concomitantly with the major occurrence of genotype 1-I for isolates obtained after oral therapy. These data attempt to consider the relevance of in vivo drug resistance for onychomycosis caused by T. rubrum.
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, PO Box 486, Belo Horizonte, Minas Gerais, Brazil. danielsantosassis@yahoo.com.br
authors.forename: Daniel
authors.initials: D
authors.lastname: de Assis Santos
authors.forename: Roberta Amália
authors.initials: RA
authors.lastname: de Carvalho Araújo
authors.forename: Lidiane Meire
authors.initials: LM
authors.lastname: Kohler
authors.forename: Jackson
authors.initials: J
authors.lastname: Machado-Pinto
authors.forename: Júnia Soares
authors.initials: JS
authors.lastname: Hamdan
authors.forename: Patrícia Silva
authors.initials: PS
authors.lastname: Cisalpino
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology* / Q000627:therapeutic use; D002675:Child, Preschool; D004271:DNA, Fungal / Q000235:genetics; D006801:Humans; D007223:Infant; D008826:Microbial Sensitivity Tests; D014009:Onychomycosis / Q000188:drug therapy / Q000382:microbiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014249:Trichophyton / Q000145:classification / Q000187:drug effects* / Q000235:genetics*
chemical_list: D000935:Antifungal Agents; D004271:DNA, Fungal