First report on autochthonous urease-positive Trichophyton rubrum (T. raubitschekii) from South-east Europe.

Background: Trichophyton raubitschekii is a dermatophyte belonging to the T. rubrum complex and is differentiated principally by its positive urease activity and production of profuse macroconidia and microconidia in culture. It is classically isolated from African, South-east Asian and Australian aboriginal patients with tinea corporis or tinea cruris.
Objectives: This study was undertaken to screen Greek and Bulgarian clinical isolates identified as T. rubrum for T. raubitschekii and to delineate these strains by two molecular methods used for the first time in T. rubrum epidemiological studies.
Methods: Ninety-five Greek and 10 Bulgarian strains, originating from various body sites, initially identified as T. rubrum, were screened for urease activity. The biochemical properties and morphology of the urease-positive strains were determined. Strains were delineated with polymerase chain reaction (PCR)-ribotyping amplifying repeat elements of the intergenic spacer region and by PCR fingerprinting.
Results: Five Greek and one Bulgarian T. raubitschekii strains were identified comprising isolates from patients with tinea manuum (one), tinea corporis (one), tinea cruris (one) and tinea unguium (three). Only one strain had the classical T. raubitschekii microscopic morphology, whereas the remaining five presented a dominant arthroconidial phenotype. Both typing methods clustered all T. raubitschekii and T. rubrum isolates together in the same group, indicating strain homogeneity in the genetic regions examined.
Conclusions: The reported isolation of T. raubitschekii in the Balkan and South-eastern Mediterranean regions extends the geographical distribution of this species. As the more primitive T. raubitschekii probably represents the parental population of T. rubrum, the Greek and Bulgarian T. raubitschekii strains could represent a remnant of the T. rubrum spread that took place after the First World War, rather than being a recent epidemiological event.