Adjunctive and comparative study between polymerase chain reaction and traditional methods for diagnosis of onychomycosis

ABSTRACT

Onychomycosis, a fungal infection of the nails by dermatophytes, yeasts, and non-dermatophyte moulds is considered the most common nail disorder in adults. Because, at present, there is no reliable, reproducible, fast and confirmatory assay for onychomycosis, we investigated the applicability of a PCR based diagnostic method. The aim of our work, to evaluate the feasibility of PCR in the diagnosis of onychomycosis and comparing the results with those of microscopy and culture .From 30 cases [17 males [56.7%] and 13 females [43.3%]] with onychomycosis, nail clippings were obtained from all cases. Microscopic examination using 20% potassium hydroxide [KOH], culture on Sabouraud's dextrose agar[SDA] with chloramphenicol medium with and without cycloheximide and PCR were used for fungal diagnosis. The number of positive cases for fungi were 19 cases [63.3%] by microscopic examination [20% KOH], 13 cases [43.3%] by culture on [SDA] [nine cases [69.3%] were non-dermatophyte molds and all are Aspergillus, one case [7.7%] was dermatophytes which was Trichophyton rubrum and three cases [23%] were yeasts] and 16 cases [53.3%] by PCR. In conclusion, non-dermatophyte molds are responsible for the majority of cases of onychomycosis, thus we can't ignore the role of non-dermatophyte molds and this may be now a consideration in evaluating and treating onychomycosis. The application of PCR technology directly to the clinical specimens will allow early, rapid and accurate diagnosis of onychomycosis but it is expensive and beyond routine investigations, meanwhile KOH examination is costless, easy and rapid but non accurate