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Antifungal susceptibility patterns of yeasts and filamentous fungi isolated from nail infection


  • Conflict of interest
    None declared.

  • Funding sources
    This study was financially supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico.

M.R.R. Silva.


Background  Onychomycosis is the nail infection caused by a wide spectrum of fungi species, including yeasts, dermatophytes and filamentous fungi non-dermatophytes (FFND). This fungal infection represents an important medical problem because it involves the patient′s life quality.

Objective  The aim was to isolate and identify the fungal agents of onychomycosis, and to determine the in vitro susceptibility to antifungal agents.

Methods  During the period of March 2008 to March 2009, 114 patients clinically suspected of having onychomycosis were examined. Demographic data, mainly age and gender were obtained from each patient. The nail samples collected (136) were submitted to direct examination with potassium hydroxide 20% and grown on Sabouraud dextrose agar. The in vitro antifungal susceptibility testing was performed according to the method of broth microdilution, recommended by the Clinical Laboratory Standards Institute (CLSI).

Results  Onychomycosis was observed in 95 (83.3%) patients, including 16 men (16.8%) and 79 women (83.2%), with mean age of 48.1 years. Candida parapsilosis, Trichophyton rubrum and Fusarium spp were the fungi most frequently isolated. The most of the isolated yeasts showed susceptibility to antifungal agents studied. Among filamentous fungi, high MIC values to itraconazole were found for T. rubrum and T. mentagrophytes, while Fusarium spp showed decreased susceptibility to itraconazole and voriconazole.

Conclusion  C. parapsilosis was the most common fungal species isolated from patients with onychomycosis. The different response obtained by in vitro susceptibility testing to drugs shows the importance of these methods to assist clinicians in choosing the best therapeutic option.