PCR Typing of Trichophyton Rubrum Isolates by Specific Amplification of Subrepeat Elements in Ribosomal DNA Nontranscribed Spacer

Trichophyton rubrum (T. rubrum) is the most common cause of dermatophytosis of skin and nail tissue. Strain identification in Trichophyton rubrum is important for identification of strain-related differences in infectivity potential or transmissibility and epidemiological studies. PCR typing could determine whether the original isolate is responsible for re-infection or a new strain has been acquired. A minipreparation method for DNA from dermatophytes was used. Tandemly repetitive subelements (TRS-1 & TRS-2) of NTS region at ribosomal DNA of 23 T.rubrum isolates were amplified and the PCR products were separated by electrophoresis in 2% agarose gel (200 mA, 140 V), visualized by staining with ethidium bromide, and photographed. On the basis of copy number of TRS-1 and TRS-2, 8 out of our 23 samples were type 2 & II, respectively. Six of them were type 3 & II, four isolates were type 1 & II, two isolates were type 4 & II, two isolates were type 1 & I and one isolate was type 5 & II. In this study, most of T. rubrum isolates were type 2 & II, dissimilar to European studies where type 1 & II has been the most common. The present study showed that 26.1% of Iranian isolates were type 1 in contrast with a previous study which has demonstrated a much lower prevalence in Asians (5%).