Molecular identification of Trichophyton mentagrophytes complex strains in Hubei province

Abstract

Objective To profile the intraspecific type of Trichophyton mentagrophytes clinically isolated from different anatomical sites of patients, and to compare the performance of different target sites for the identification of Trichophyton mentagrophytes complex strains. Methods A total of 48 Trichophyton mentagrophytes strains, which were clinically isolated from Department of Dermatology, Wuhan No. 1 Hospital in the latest 3 years, were included in this study. The phenotypes of these Trichophyton mentagrophytes isolates were primarily determined by morphological observation and the urease test. PCR was performed to amplify the nuclear ribosomal internal transcribed spacer (ITS) region and the D1-D2 domains of the large-subunit ribosomal DNA (28S rDNA) followed by DNA sequencing. Then, Clustal X2 software and MEGA 6.0 software were used to analyze the ITS and D1-D2 sequences and to build phylogenetic trees by the maximum-likelihood method (bootstrap= 2000) . Results As the ITS sequence-based phylogenetic tree showed, the probability that the 48 isolates were grouped into the Trichophyton interdigitale clade reached 92%. However, Trichophyton interdigitale could not be effectively differentiated from Trichophyton quinckeanum by the D1-D2 sequence-based phylogenetic tree. In addition, Trichophyton interdigitale showed various appearances, including woolen type, downy type, cream type, powdery type and granular type. Conclusions Trichophyton mentagrophytes can be identified to the species level based on the sequence of ITS region, which shows higher efficiency in identifying Trichophyton mentagrophytes complex than the D1-D2 domains. Morphological characteristics can not serve as the basis for intraspecific typing of Trichophyton mentagrophytes. Key words: Trichophyton; DNA barcoding, taxonomic; DNA, ribosomal spacer; Ribosome subunits, large; Mycological typing techniques