Divergence Among an International Population of Trichophyton tonsurans Isolates
Trichophyton tonsurans is a widely distributed pathogen that demonstrates a significant degree of genetic and phenetic heterogeneity. To date, the degree of genetic relatedness among geographically segregated isolates has not been explored. This investigation evaluates the extent of genetic variation among an international population of T. tonsurans isolates and examines the relatedness of isolates within and between countries. Molecular strain typing was performed on 198 isolates obtained from 14 countries. A mixed-marker strategy utilizing 27 sequence variations in 13 gene loci was applied to all isolates and cluster analysis was performed to examine the relationship between strains. Phylogenetic analysis was used to corroborate the findings of the cluster analysis with T. equinum strains serving as an out-group. In total, 47 distinct strain types were identified represented by seven clusters and one singleton. There appeared to be a moderate degree of clustering among isolates obtained from North America, Asia and Australia, although European isolates were uniformly distributed among the majority of clusters. The degree of genetic variation observed in this study coupled with the geographic localization would support the argument for allopatric divergence within this species.
KeywordsDermatophyte Trichophyton tonsurans Trichophyton equinum Strain typing
- 28.Felsenstein J. PHYLIP (Phylogeny Inference Package), version 3.68. Distributed by the author. Department of Genome Sciences, University of Washington, Seattle; 2006.Google Scholar
- 31.Mochizuki T, Kawasaki M, Anzawa K, Fujita J, Ushigami T, Takeda K, et al. Epidemiology of sporadic (non-epidemic) cases of Trichophyton tonsurans infection in Japan based on PCR-RFLP analysis of non-transcribed spacer region of ribosomal RNA gene. Jpn J Infect Dis. 2008;61:219–22.PubMedGoogle Scholar
- 40.Donald GF. A warning on the frequency of endothrix tinea capitis among the Aboriginal and part-aboriginal population of South Australia. Med J Aust. 1959;2:435–6.Google Scholar