Phylogenetic Classification and Species Identification of Dermatophyte Strains Based on DNA Sequences of Nuclear Ribosomal Internal Transcribed Spacer 1 Regions

摘要

The mutual phylogenetic relationships of dermatophytes of the genera Trichophyton, Microsporum, andEpidermophyton were demonstrated by using internal transcribed spacer 1 (ITS1) region ribosomal DNA sequences.Trichophyton spp. and Microsporum spp. form a cluster in the phylogenetic tree with Epidermophyton floccosum as an outgroup, and within this cluster, allTrichophyton spp. except Trichophyton terrestreform a nested cluster (100% bootstrap support). Members of dermatophytes in the cluster of Trichophyton spp. were classified into three groups with ITS1 homologies, with each of them being a monophyletic cluster (100% bootstrap support). TheArthroderma vanbreuseghemii-Arthroderma simii group consists of A. vanbreuseghemii, A. simii,Trichophyton mentagrophytes isolates from humans, T. mentagrophytes var. quinckeanum, Trichophyton tonsurans, and Trichophyton schoenleinii. Arthroderma benhamiae, T. mentagrophytes var.erinacei, and Trichophyton verrucosum are members of the Arthroderma benhamiae group.Trichophyton rubrum and Trichophyton violaceumform the T. rubrum group. This suggests that these “species” of dermatophytes have been overclassified. The ITS1 sequences of 11 clinical isolates were also determined to identify the species, and all strains were successfully identified by comparison of their base sequences with those in the ITS1 DNA sequence database.