Onychomycosis in São Paulo, Brazil

Abstract

Onychomycosis is a fungal infection of the nails with broad aetiological scope, and it represents 18-40% of all onychopathies and 39% of all superficial mycotic infections. From July 1996 to December 1999, samples of nails were collected from 588 patients with presumptive diagnosis of onychomycosis at the Dermatology and Mycology Divisions EPM\UNIFESP, Brazil, and the diagnosis was confirmed in 247 of these cases. The most common pathogens isolated in this study were yeasts in 52% of positive cultures (Candida albicans 18.3%, Candida parapsilosis 13.8%, other species of Candida 15.4% and other yeasts 4.6%), followed by dermatophytes in 40.6% of positive cultures (the most commonly isolated organisms were Trichophyton rubrum in 33.2%, followed by Trichophyton mentagrophytes in 6.3% and others 1.2%). Non-dermatophyte moulds were isolated in 7.4% of positive cultures (Fusarium spp. 4.5%, Nattrassia mangiferae 2.3% and Aspergillus spp. 0.6%). Distal and lateral subungual onychomycosis (DLSO) was the commonest clinical pattern 44.6% followed by free edge onycholysis (FEO) 38.8% and others. In conclusion, this study demonstrated that T. rubrum is the main agent causing onychomycosis in toenails, and species of genus Candida were the main agents isolated in fingernail onychomycosis in our region.

Dermatophytosis: a 16-year retrospective study in a metropolitan area in southern Brazil

“…It is commonly found in all regions of the body, except on the scalp, where M. canis predominates. It was observed that toenails were more affected by dermatophytes than fingernails, also in agreement with the literature [28,29]. Toenails were more affected by the genus Trichophyton than was the foot skin, unlike E. floccosum, which was more prevalent in the skin than in the nails, corroborating the literature data [19,30].…”

Systematic review of nondermatophyte mold onychomycosis: Diagnosis, clinical types, epidemiology, and treatment

“…Although the vast majority of studies use a preparation containing 5% to 40% KOH for microscopic observation of nail samples or scrapings, sodium sulfide 9 or sodium hydroxide 10 may be substituted. In addition, Parker's blue-black permanent ink (Parker Pen Company, Newhaven, UK) 11,12 or fluorescent agents 9 may be added to enhance visualization. Although KOH preparation provides a rapid screening test for fungi, and may even assist in their identification, 13,14 it can be associated with false-negative results, 15,16 and does not demonstrate viability or causative nature of the isolated fungal elements.…”

“…The resulting colonies are identified by microscopic and macroscopic details, according to identification keys. 11 Although fungal culture demonstrates viability and allows the identification of isolated fungi, it is time-consuming, may be associated with a high rate of false-negative results, 9,18 and does not distinguish causative agents from contaminants.…”

Dermatófitos: interação patógeno-hospedeiro e resistência a antifúngicos

“…11 Among onychomycoses, T.rubrum is also the most prevalent dermatophyte, affecting children and adults in about 33.2% of the cases identified in Sao Paulo, followed by T. mentagrophytes (6.3%). 12 In Fortaleza, a three-year study described the isolation of dermatophytes in 12.99% of the cases of onychomycosis; T. rubrum was isolated in 9.04% of the patients and T. tonsurans and T. mentagrophytes, in 2.54% and 1.41%, respectively. 13 …”