Species Distinction in the Trichophyton rubrum Complex

Huilin Su, Ann Packeu, Sarah A Ahmed, Abdullah M S Al-Hatmi, Oliver Blechert, Macit İlkit, Ferry Hagen, Yvonne Gräser, Weida Liu, Shuwen Deng, Marijke Hendrickx, Jinhua Xu, Min Zhu, Sybren de Hoog

Research output: Contribution to journal/periodicalArticleScientificpeer-review

Abstract

The Trichophyton rubrum species complex comprises commonly encountered dermatophytic fungi with a worldwide distribution. The members of the complex usually have distinct phenotypes in culture and cause different clinical symptoms, despite high genome similarity. In order to better delimit the species within the complex, molecular, phenotypic, and physiological characteristics were combined to reestablish a natural species concept. Three groups, T. rubrum, T. soudanense, and T. violaceum, could be distinguished based on the sequence of the internal transcribed spacer (ITS) ribosomal DNA barcode gene. On average, strains within each group were similar by colony appearance, microscopy, and physiology, but strains between groups showed significant differences. Trichophyton rubrum strains had higher keratinase activity, whereas T. violaceum strains tended to be more lipophilic; however, none of the phenotypic features were diagnostic. The results of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and amplified fragment length polymorphism (AFLP) were partially consistent with the ITS data but failed to distinguish the species unambiguously. Despite their close similarity, T. violaceum, T. soudanense, and T. rubrum can be regarded as independent species with distinct geographical distributions and clinical predilections. Trichophyton soudanense is pheno- and genotypically intermediate between T. rubrum and T. violaceum For routine diagnostics, ITS sequencing is recommended.

Original languageEnglish
JournalJournal of Clinical Microbiology
Volume57
Issue number9
DOIs
Publication statusPublished - Sep 2019

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