Molecular typing ofTrichophyton mentagrophytesvar.interdigitaleisolated in a university hospital in Japan based on the non‐transcribed spacer region of the ribosomal RNA gene

Abstract

Detecting intraspecies polymorphisms in fungi causing dermatophytoses is important in elucidating routes of infection and determining whether Tinea recurrence is caused by exacerbation or re-infection. In fungi, the non-transcribed spacer region (NTS) of the ribosomal RNA gene shows the greatest accumulation of base sequence mutations. We therefore assessed NTS sequences in 64 clinical isolates of Trichophyton mentagrophytes var. interdigitale, the second most common species of dermatophytes in Japan. These isolates were among the clinical isolates of dermatophytes in the Department of Dermatology, Kanazawa Medical University Hospital in 2006 and were obtained by morphological and molecular biological identification methods. DNA was extracted from each isolate, as well as from one isolate maintained in our department, to detect length polymorphisms at each of three variable loci, TmiS0, TmiS1 and TmiS2, of the NTS for subtyping. We observed seven patterns for TmiS0, six patterns for TmiS1 and three patterns for TmiS2. The combinations of these patterns enabled us to classify the 65 isolates into 15 types. The most prevalent, constituted 46% (30/65) of all isolates. Eleven types were new combinations, whereas the other four were previously described. These results suggest that this method may be used to determine the molecular epidemiology of T. mentagrophytes var. interdigitale in Japan, because it generated results rapidly and in a sensitive manner.

Molecular Epidemiology of a Major Subgroup of Arthroderma benhamiae Isolated in Japan by Restriction Fragment Length Polymorphism Analysis of the Non-Transcribed Spacer Region of Ribosomal RNA Gene

“…However, analysis of the non-transcribed spacer (NTS) region of the rRNA genes has been reported to be a more robust technique for strain typing of some dermatophyte species, such as Trichophyton rubrum (8), Trichophyton tonsurans (9-12), and T. mentagrophytes var. interdigitale (13)(14)(15). Our previous study indicated that Southern blot hybridization of the NTS region is useful for the discrimination of A. benhamiae strains (16), and simple molecular methods are required to be developed for this purpose.…”

Genetic Relationship between Trichophyton mentagrophytes var. interdigitale and Arthroderma vanbreuseghemii

“…All of the clinical isolates of T. mentagrophytes var. interdigitale assayed showed homogeneous mitochondrial DNA genotype, the same as that of A. vanbreuseghemii and different from those of two other teleomorphs of T. mentagrophytes, A. benhamiae and A. simii 8) . On the other hand, the genotypes of ITS were also homogeneous among 64 T. mentagrophytes var.…”

“…interdigitale 4,8) . lesions related in animals are granular to powdery cultures and identified as T. mentagrophytes var.…”

“…Total DNA was prepared from each isolate using a modification of the method reported previously 8) . Briefly, small samples of mycelia were suspended in 200 μl of extraction buffer, boiled for 5 min, 100 μl of 3 M sodium acetate was added, and then DNA was precipitated by adding 300 μl of isopropanol and centrifugation at 19,000 ×g for 20 minutes.…”

“…interdigitale was investigated by restriction enzyme analysis of mitochondrial DNA, and all of 22 isolates showed band patterns identical to those of A. vanbreuseghemii 8) . On the other hand, the band patterns of T. mentagrophytes var.…”