[Trichophyton thuringiense H.A. Koch 1969. A rare geophilic dermatophyte--now isolated for the first time from man].

Background: In 1969, Kolipp and Hoffmann isolated Trichophyton (T.) thuringiense spec. nov. Koch when they performed their thesis dealing with the distribution and epidemiology of dermatophytes and keratinophilic fungi in mice and other small mammals. At that time, T. thuringiense was detected as saprophytic fungus of the skin of different mice species (e.g. Mus musculus) both in rural and urban settings in the area of Thuringia in Germany. There were no further reports on this dermatophyte species until now, neither in animals, nor in man.
Patient, Methods and Results: Currently, we were able to isolate this geophilic fungus for the first time from a human being. A 58 year old patient baker by trade and living in a rural setting (village) suffered from nail changes like hyperkeratosis and thickening of the nail plate of his big toe. From his nail samples grew a dermatophyte with peripheral radiating and flat colonies which were a bit cottony in the centre. On Sabouraud's 4 % dextrose agar the thallus of the fungus was white to purple stained, the reverse side showed a dark red to brown color. In a typical manner, macroconidia were cylindrical to clavate, microconidia obovoidal to short-clavate with broad base. The species identification of T. thuringiense was done and confirmed by sequence analysis of the internal transcribed spacer (ITS) region of the ribosomal DNA. Antifungal treatment has been refused from the patient.
Conclusion: In conclusion, this is the second description of the geophilic dermatophyte T. thuringiense, which could be isolated for the first time from a human being, in particular from nail sample of the big toe under the suspicion of onychomycosis. However, it is still uncertain if this fungus should be considered either as secondary colonization of the nail plate, or as causative agent of tinea unguium or onychomycosis.