Species Distinction in the Trichophyton rubrum Complex

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.

A Comparative Study on Phenotypic versus ITS-Based Molecular Identification of Dermatophytes Isolated in Dakar, Senegal

“…e T. soudanense group included T. circonvolutum, T. gourvilii var. intermedium, and T. gourvilii, and the T. rubrum group contained type strains of T. fischeri, T. flavum, T. fluviomuniense, T. kanei, T. pedis, T. raubitscheckii, and T. rodhainii, all of which, consequently, can be regarded as proven synonyms of T. rubrum [18]. International Journal of Microbiology According to the database, T. soudanense was identified as such or as T. rubrum (African population).…”

“…erefore, the anatomical site of isolation could be very useful as a criterion for orienting because T. violaceum and T. soudanense are prevalently found on the scalp (80.85% and 71.43% of strains from human sources, respectively), whereas T. rubrum is mostly found on glabrous skin (6.98% of strains from human sources) [18]. Because of the increased traveling and migration of people, the geographical origin of the strains is less reliable.…”

“…Because of the increased traveling and migration of people, the geographical origin of the strains is less reliable. With certain minor exceptions, it was found that T. rubrum and T. violaceum have a global distribution, whereas T. soudanense is limited to Africa [18]. However, T. violaceum is mainly found around the Mediterranean basin (particularly in North Africa), as well as in Central Africa, the Middle East, and Eastern Europe [10].…”

A rapid and accurate method for the detection of four aminoglycoside modifying enzyme drug resistance gene in clinical strains of Escherichia coli by a multiplex polymerase chain reaction

“…Therefore, rapid and accurate methods for the detection of bacterial resistance are urgently needed, and the use of antibiotics or antibiotic therapy should be more standardized and technically, where possible, monitored. With the development of molecular biology and bioinformatics, the detection methods of bacterial drug resistance genes, including PCR, loop-mediated isothermal amplification, and whole genome sequencing (WGS) (Moran et al, 2017;Su, Satola & Read, 2019), have increased (Tamburro & Ripabelli, 2017). Although WGS is gradually reaching maturity, while sequencing costs are drastically decreasing, it is however still relatively costly, complex in operation and requires for analysis specialized personnel like bioinformaticians, which limits its popularization and application (Quainoo et al, 2017).…”

Genotyping of Russian isolates of fungal pathogenTrichophyton rubrum, based on simple sequence repeat and single nucleotide polymorphism

“…All of these can be differentiated by ribosomal DNA internal transcribed spacer (ITS) region sequences. [2][3][4][5][6] Statistical analysis of genetic polymorphism in simple sequence repeats (SSR, or microsatellites) revealed clonal mode of reproduction in the species. [7][8] It is expectedly accompanied by low genetic polymorphism.…”