الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Background: Onychomycosis is a common nail disorder, represents 50% of onychopathies and about 30% of mycotic cutaneous infections. Onychomycosis requires administration of antifungal agents for long periods. Several nail disorders may mimic to onychomycosis clinically. Therefore sensitive, quick and inexpensive test is essential for screening nail specimens. In our labs we commonly diagnose onychomycosis using potassium hydroxide (KOH) preparation and culture. These tests are either time-consuming or require specially trained personnel. A recently developed polymerase chain reaction (PCR) assay has the potential to provide a quick and inexpensive method for diagnosis of onychomycosis. We studied all these different methods in the diagnosis of onychomycosis with special concern on tinea unguium diagnosis.
Aim : The aims of this study were to compare KOH preparation, calcofluor white stain (CFW), culture and PCR in the diagnosis of onychomycosis and to determine their sensitivity, specificity, positive predictive value and negative predictive value.
Methods: Nail specimens were collected from patients clinically suspected of onychomycosis. They were examined by 20% KOH, CFW microscopic examination, cultured on Sabouraud’s dextrose agar (SDA) containing chloramphenicol with/without cyclohexamide and dermatophytes test media (DTM) and lastly nail specimen were subjected to DNA extraction and PCR which was carried out using pan-fungal, pan-dermatophyte, Trichophyton rubrum-specific primers.
Results: Of the 76 patients, 54 had at least 1 of the 4 diagnostic methods positive for the presence of organisms. Culture was positive only in 46 (46.9%) of nail samples. The most common isolated organisms were Candida albicans (36.9%) followed by Aspergillus spp. (26.1%). Using culture as gold test, sensitivity of KOH, CFW and PCR was 85%, 100%, and 100% respectively while specificity of KOH, culture and PCR was 69%, 67%, and 63% respectively.
Conclusion: The application of PCR technology directly to the clinical specimens will allow early and accurate diagnosis of onychomycosis.