[Onychomycosis-causing yeasts in four Mexican dermatology centers and their antifungal susceptibility to azolic compounds].

Background: Yeasts represent the second cause of nail fungal infection in the world, and Candida albicans and Candida parapsilosis are the two most common species.

Objectives: To determine the yeast species frequency and their in vitro antifungal susceptibility, obtained from patients with clinical features suggestive of onychomycosis.

Methods: A prospective study was carried out in four dermatological care centers in Mexico from 2004 to 2007. Clinical diagnosis was corroborated by direct examination and culture. The yeast species was determined by morphological and biochemical tests. An antifungal susceptibility test to ketoconazole, itraconazole and fluconazole by the broth microdilution method was performed on each isolate (document M27-A2).

Results: One hundred sixty-six yeast isolates were obtained; the most frequently found species were C. parapsilosis (31.9%), C. albicans (22.4%) and Candida guilliermondii (12.7%). Of all isolates, 51 showed resistance to one or several of the azole compounds: 33 to itraconazole, 12 to ketoconazole and 6 to fluconazole. It was remarkable that the four Candida glabrata isolates were resistant to the three azole compounds; C. guilliermondii and Candida famata were resistant to itraconazole in 42.9% and 54.5%, respectively.

Conclusion: The results obtained show the importance of identifying the aetiological agent and antifungal susceptibility testing in order to avoid therapeutic failures in onychomycosis.