Knowledge of epidemiological and mycological characteristics of onychomycosis has been noted by many authors as being an important tool for control of these fungal infections. This study seeks to improve knowledge of onychomycosis epidemiology and mycological features. Samples were taken from infected fingernails and toenailsOnychomycosis is a denomination used to describe nail infection usually caused by dermatophytes, yeast, and non-dermatophytic moulds (Mercantini et al. 1996, Weitzman & Summerbell 1996. These fungi may cause onychomycosis particularly as secondary invaders after damage by trauma or disease (Haneke 1991, Elewski 1998.Onychomycosis affects approximately 5% of the population worldwide (Murray & Dawber 2002) and represents around 30% of all superficial mycotic infection (Migdley et al. 1994) and 50% of nail disorders (Drake et al. 1996, Ghannoum et al. 2000.Dermatophytes are responsible for nearly 90% of toenail onychomycosis and at least 50% of fingernail infections (Elewski 1998). Candida species, particularly C. albicans, prevail in fingernail infections (Lopes et al. 1999, Pontes et al. 2002. Non-dermatophytic moulds are rare, but a number of species, such as Fusarim spp., Scytalidium spp., and Acremonium spp. have also been described as etiological agents of onychomycosis (Migdley et al. 1994, Tosti et al. 2000, Pontes et al. 2002.The epidemiology of onychomycosis has been well studied in some countries, but few data are available in tropical countries (Kam et al. 1997). In addition, research on this theme is poorly exploited in Northeast Brazil. This study, therefore, seeks to improve knowledge of the epidemiology and the mycological features of onychomycosis. Specimen collection and processing -The specimens were obtained from clinically abnormal nails, by a vigorous scraping of the nail bed, the underside of the nail plate and the hyponychyum, after cleaning the affected areas with 80% ethanol. The samples of each patient were placed in separate sterile Petri dish and transported to Medical Mycology Specialized Center. Scales scraped from the nails were analyzed for fungal elements, such as hyphae or blastoconidia, by direct microscopy examination, in potassium hydroxide (30%). For fungal cultures, all samples were inoculated on each of three isolation media (i) Sabouraud glucose agar (SGA; Difco Laboratories, Detroit, MI), (ii) SGA with 5% chloramphenicol, and (iii) Mycosel agar (Sanofi, France). The culture tubes were incubated at 28°C and examined daily for one month. Specimens from the lesions were repeatedly collected three times when it was observed growth of a nondermatophyte alone from a specimen that has tested positive for fungi on direct microscopy.Strain identification -The yeast isolates were identified according to morphological characteristics and the biochemical profile. To determine yeast micromorphology, cornmeal-Tween 80 agar plates were streaked and stabbed with a 48-h-old yeast colony, covered with a sterile cover-

Onychomycosis is a fungal infection of nails caused by dermatophytes, yeasts and moulds, accounting for about 50% of onychopathies. A high frequency of onychomycosis caused by Candida species has been reported during the last few years in northeast Brazil, as well as in other regions of the world. A clinical diagnosis of onychomycosis needs to be confirmed through laboratory exams. We evaluated the importance of serial repetition of direct microscopic exams and fungal culture for the diagnosis of onychomycosis in the city of Fortaleza, Ceará, in northeast Brazil. We first made a retrospective study of 127 patients with onychomycosis, identifying the fungi that had been isolated from fingernails and toenails. We then made a prospective study of 120 patients, who were submitted to three successive mycological examinations. Ungual residues were scraped off and directly examined with a microscope and fungal cultures were made. In the retrospective study, in which only one sample was analyzed, the incidence of onychomycosis was 25.0%. In our prospective study, in which we had data from successive mycological examinations, 37.8% had onychomycosis. The most commonly isolated fungi in both studies were yeasts from the genera Candida, especially C albicans, C. parapsilosis and C. tropicalis. We found a high proportion of onychomycosis caused by Candida species. We also concluded that serial repetition of direct microscopic examination and fungal culture, with intervals of 2-5 days improved the diagnosis of onychomycosis. We suggest that this laboratorial strategy is necessary for accurate diagnosis of this type of mycosis, especially when the standard procedures fail to diagnose fungal infection, despite strong clinical suspicion.

Our data show that T. tonsurans is the main etiologic agent of tinea capitis, and is more likely to be found in females and in the prepubertal population.