Molecular Strain Typing of Trichophyton Rubrum Isolated from Patients with Onychomycosis by Polymerase Chain Reaction(PCR)

Dermatophytes are a group of keratinophilic fungi falling within the genera of epidermophyton, microsporum and trichophyton. The genus trichophyton is particularly important and complex which comprises at least 24 recognised species. Additionally, molecular strain typing of trichophyton rubrum isolated within single nail specimens from patients with onychomycosis indicates involvement of multiple strains. In this study, nail specimens from patients with onychomycosis were cultured and 10 specimens from different patients with 5 colonies per culture plate were selected. Deoxyribonucleic acid(DNA) was extracted from these isolates and subjected to a PCR-based typing method that analysed variations in numbers of repeats in the non-transcribed spacer(NTS) region of the ribosomal ribonucleic acid(rRNA) gene repeats. In 6 out of 10 specimens, there were 2 or more strain types. This suggests that in the majority of cases of fungal nail infections by trichophyton rubrum, multiple strains are involved. This has important implications for epidemiological studies.