Onychomycosis accounts for up to 50%of all nail disorders. They can be caused by: yeasts, dermatophytes and non-dermatophyte moulds.
A multicentre study designed to determine the prevalence, mycological test results, aetiological agents, and clinical presentation of onychomycosis was carried out. All fingernail and toenail samples taken during a one year period at 9 diagnostic centres were included.
A total of 5,961 samples were analysed, of which 82.3%were from toenails and 17.7%from fingernails. The mean age of the patients was 49.7 years, and 66%were females. Direct microscopic examination was positive in 61%of the samples. In adults, 61.2%of toenails were positive using potassium hydroxide (KOH), and 43.7%were positive in cultures. The prevailing aetiological agents belong to the dermatophyte group (82.8%), and distal subungual was the most common clinical form. In fingernails, direct examination showed 59.8%positive samples, and cultures were positive in 52.9%. The prevailing agents were yeasts belonging to Candida species, and onycholysis was the most common lesion.
Direct mycological examinations were positive in 61%, a higher value than that found in other series. Dermatophytes were prevalent in toenails of both sexes, and in finger nails yeast were prevalent in females, and dermatophytes in males. Non-dermatophyte moulds corresponded to 4.8%of toenail and 2.05%of fingernails isolates.