Background and Aim: Dermatophytes are the group of keratinophilic fungi that can cause diseases and infection in skin and other keratinized parts such as nail and hairs. The most important genus among keratinophilic fungi is Trichophyton which can be the most probable cause of tinea pedis in the world. There are 24 recognized species of this genus. Additionally, molecular strain typing of Trichophyton mentagrophytes isolates within skin specimens from patients with dermatophytosis indicates involvement of multiple strains. The aim of this study was the determination of strains of Trichophyton mentagrophytes in order to prevent the dissemination of infection,which is very important epidemiologically.

  Materials and Methods: The study was of descriptive – analytic type. Skin specimens from 100 patients who had dermatophytosis by Trichophyton mentagrophytes were cultured and plates which had 5 colonies were selected. Deoxyribonucleic acid (DNA) was extracted from the isolates. According to PCR-based typing method that analysed variations in the numbers of repeats in the non-transcribed spacer(NTS) region of the ribosomal ribonucleic acid(rRNA) gene repeats, data were described. All the results were analyzed by (± SD) , Chi –square and t-student tests.

  Results: In 20 out of 100 specimens of Trichophyton mentagrophytes , there were 2 or more strain types in a variety of Trichophyton mentagrophytes .

  Conclusion: These results suggest that in the most cases of fungal infections caused by Trichophyton mentagrophytes, multiple strains are involved. These results have important implications in epidemiological studies,treatment and drug resistance in fungal infection.