Les dermatophytes : les difficultés du diagnostic mycologique

Dermatophytes are filamentous fungi that are responsible for various diseases affecting glabrous skin, nails or hair, of which diagnosis is not clinically obvious. Therefore, when a dermatophytosis is suspected, a mycological analysis is very often required. Nevertheless, although this analysis is usually performed in most of medical laboratories, the demonstration of a fungal aetiology is not easy. Indeed, to reach a reliable result, the biologist has to overcome successive difficulties : 1. specimen collection according to lesions, 2. direct examination of samples followed by cultures 3. identification of isolated fungi, 4. interpretation of results. The difficulties that may be encountered in the different steps of the diagnosis of dermatophytosis rely essentially on the absence of standardisation of specimen collection and mycological techniques, and on the lack of commercially available specific culture media. Authors will review the main difficulties to overcome.