Molecular strain typing of Trichophyton mentagrophytes (T. mentagrophytes var. interdigitale) using non-transcribed spacer region as a molecular marker

Background & objectives : Dermatophytes are keratinophilic fungi that infect keratinized tissues of human and animal origin. Trichophyton mentagrophytes is considered to be a species complex composed of several strains, which include both anthropophiles and zoophiles. Accurate discrimination is critical for comprehensive understanding of the clinical and epidemiological implications of the genetic heterogeneity of this complex. Molecular strain typing renders an effective way to discriminate each strain. The objective of the study was to characterize T. mentagrophytes clinical isolates to sub-species level using molecular techniques and non-transcribed spacer (NTS) region as marker. Methods Sixty four T. mentagrophytes clinical isolates were identified by phenotypic methods. These were subjected to polymerase chain reaction targeting three sub-repeat elements (SREs), TmiS0, TmiS1 and TmiS2 of the NTS region. Sequence analysis of internal transcribed spacer (ITS) region of different types was also done. Results Strain-specific polymorphism was observed in all three loci. Totally, 13 different PCR types were obtained on combining all the three SREs loci. No variation was observed in the ITS region. Interpretation & conclusions The study described the usefulness of molecular strain typing technique for the discrimination of the T. mentagrophytes isolates. This will help for the future explorations into the epidemiology of T. mentagrophytes and its complex.