DNA topoisomerase 2 gene polymorphism in dermatophytes

Abstract

Summary Background Dermatophytes are a group of keratinophilic fungi of medical importance. Despite a relatively long history of molecular taxonomic studies, there is still a need for information on genetic polymorphism in wider variety of genomic loci. Objectives Our goal was to study partial DNA topoisomerase 2 gene (TOP2) polymorphism in dermatophytes. Methods We performed DNA sequencing of TOP2 in 26 dermatophyte species along with ribosomal internal transcribed spacer (ITS) sequencing. Results The number of polymorphic sites in TOP2 data set was similar to that one in ITS data set. Nannizzia species formed paraphyletic group in TOP2 tree. Trichophyton simii was paraphyletic in concatenated TOP2‐ITS tree, one of its two clades contained solely Iranian isolates. Conclusions Our results revealed several unresolved problems in the taxonomy of dermatophytes, including probable polyphyly of the genus Nannizzia and the species T simii.

The unprecedented epidemic-like scenario of dermatophytosis in India: II. Diagnostic methods and taxonomical aspects

“…16,29,30 Recently it was also found to have unique Topoisomerase 2 (TOP2) sequence type, underlining the fact that this distinct Indian ITS and TOP2 genotype are part of the T. mentagrophytes clade and not a 'cryptic' new species. 31 A striking resemblance to this genotype has also been found in those demonstrated in Iran and Oman. 32 This particular study performed in 2016 also referred to the strains as T. interdigitale, because it followed the former taxonomy.…”

“…Type VII (Thai variant) and VIII (India) exhibit anthropophilic behavior of human to human transmission. 31 T. mentagrophytes Type VII (Thai variant) is genetically within the clade of T. mentagrophytes, and bears a morphological similarity too. However its transmission in abscessing tinea pubogenitalis does not occur from animals, The fungus is transmitted, without exception, from human to human as an agent of what is now considered a sexual transmitted infection.…”

Spread of Terbinafine-Resistant Trichophyton mentagrophytes Type VIII (India) in Germany–“The Tip of the Iceberg?”

“…mentagrophytes / T . interdigitale complex [ 16 , 21 , 25 , 26 , 27 , 28 , 29 , 30 ] ( Figure 5 a–d). Therefore, it does not appear justifiable to attempt assigning this single genotype VIII of T .…”

“…T. mentagrophytes Type VIII is only one variety within the cluster of a large number of genotypes of the T. mentagrophytes/T. interdigitale complex [16,21,[25][26][27][28][29][30] (Figure 5a-d). Therefore, it does not appear justifiable to attempt assigning this single genotype VIII of T. mentagrophytes to a brand new species, so hurriedly, on the basis of just two isolated terbinafine-resistance isolates of T. mentagrophytes, disregarding the plethora of literature on a well-accepted taxonomy and nuances of this genotype, as has just happened in an isolated publication from Japan [31].…”

On the new classification of dermatophytes

“…Дерматофиты являются сложным для изучения объектом, поскольку генетически удалённые формы, например Trichophyton mentagrophytes и Trichophyton benhamiae, могут обладать схожими морфологическими признаками и экологическими свойствами. И наоборот, практически идентичные с точки зрения генотипа Trichophyton tonsurans и Trichophyton equinum хорошо различаются по своей эпидемиологии [33]. В связи с этим для выделения видов невозможно использовать условный процент сходства нуклеотидных последовательностей, принятый в бактериологии [34] и вирусологии [35].…”