First identification of Trichophyton rubrum var. raubitschekii in Constantine (ALGERIA).

Onychomycosis is a nail infection caused by different fungal belonging to dermatophytes, yeasts and molds. Dermatophytes are the most incriminated. The aim of our study is to establish both conventional and molecular diagnosis for onychomycosis in Constantine. Sixteen nail samples were collected from patients with nail lesions, clinically suspected of onychomycosis. Direct microscopic observation and culture on Sabouraud medium with and without cycloheximide were performed. The identification was based on macroscopic and microscopic features, and confirmed by real-time panfungal PCR analysis. The ITS1-5.8S-ITS2 rDNA region was amplified using the ITS1 and ITS4 primers; and sequenced. The 16 samples were positive on their KOH direct examination. On Sabouraud medium, only 5/16 gave positive culture. The urease test on Christensen medium performed on the 5 isolates revealed a positive urease for one isolate and showed numerous macroconidia in microscopic observation. This isolate showed 99 % of homology with both Trichophyton raubitschekii JX827168.1 and Trichophyton rubrum FM178326.1 in molecular diagnosis. Based on phenotypical characteristics and molecular analysis, this isolate was identified as a Trichophyton rubrum var. raubitschekii. The ITS phylogenetic tree, showed 100 % of homology in the ITS region of Trichophyton rubrum, and Trichophyton raubitschekii isolated. The systematic use of the urease test for Trichophyton rubrum could contribute to increase the prevalence of Trichophyton rubrum var. raubitschekii in the world.