Isolation ofTrichophyton rubrumvar. raubitschekii from a dog

Generalized superficial mycosis caused by Trichophyton raubitschekii in China: case report and review of the literature

This is a generalized superficial mycosis case from which Trichophyton raubitschekii was isolated. A male adult was presented with a 3-year history of fingernail and toenail changes, and a 50-day history of severe and multiple skin lesions. He also complained of intense itching. T. raubitschekii was identified from every skin lesion (trunk, extremities and nail) through microscopic examination, physiological experiment and DNA sequencing. Generalized superficial mycosis was diagnosed and treated by administering a combination of oral (terbinafine tablets) and topical (naftifine hydrochloride and ketoconazole cream) antimycotic drugs. After treatment, the patient was cured and no recurrence has been observed.

Urease gene of Trichophyton rubrum var. raubitschekii

The recent description (in GenBank) of a urease-encoding gene from Trichophyton rubrum provides an opportunity to compare this species to the highly similar T. rubrum var. raubitschekii. Therefore, the corresponding genomic DNA was recovered from T. rubrum var. raubitschekii, and the sequence and expression were compared for this urease gene in urease-positive and -negative isolates of T. rubrum and T. rubrum var. raubitschekii. The sequence (2371 bp) of the T. rubrum var. raubitschekii urease gene revealed the presence of three exons. Except for a three-amino acid insertion, the predicted proteins were identical, but demonstrated protein identity of approximately 70% compared to an Arthroderma gypseum homolog. Reverse transcription polymerase chain reaction analysis revealed the presence of a corresponding transcript in both urease-positive T. rubrum var. raubitschekii isolates examined; the same analysis did not detect this transcript in urease-negative isolates of T. rubrum.

Epidemiological aspects of Trichophyton rubrum var. raubitschekii in Japan

Trichophyton rubrum var. raubitschekii is a rare anthropophilic dermatophyte isolated around the world from tinea corporis, tinea cruris, tinea pedis and tinea unguium. In this study, the isolation rate of T. rubrum var. raubitschekii was studied in 200 cases of tinea pedis and tinea unguium in Japan. The 200 clinical isolates were shown to be of downy type as their colonies on Sabouraud's dextrose agar were white to cream, suede-like to downy, with a yellow-brown to wine-red reverse, and they produced few macroconidia. The type strain of T. rubrum var. raubitschekii (CBS 100084) and one clinical isolate (KMU 8337; isolated at Kanazawa) of downy type tested positive for urease, but the reference strain of T. rubrum (CBS 392.58) and the remaining 199 clinical isolates tested negative. Further epidemiological investigations are required to study human cases of infection with the granular type of T. rubrum and T. rubrum var. raubitschekii in Japan.