Microsatellite markers reveal geographic population differentiation in Trichophyton rubrum.

A worldwide selection of more than 200 isolates of the anthropophilic dermatophyte Trichophyton rubrum were analysed using seven microsatellite markers. Fifty-five multilocus genotypes were recognized, allowing a subdivision of the species into two populations. Both populations reproduced strictly clonally, showed a different predilection on the human host (scalp vs foot) and displayed geographic differentiation. Genotypes of one population originated predominantly from Africa, whilst the second population showed a worldwide distribution excluding the African continent. Genotypic diversity was highest in the African population, despite the lower number of strains analysed, suggesting that T. rubrum is likely to have evolved in Africa. No diagnostic correlation was observed between multilocus genotypes and any of the phenotypical characteristics of the strains. The involvement of multiple strains in a single patient detected by workers using other typing methods was not supported by these microsatellite markers. Four of the developed microsatellite markers may be applied for diagnostic purposes.