Diagnosis of onychomycosis made simple

Because onychomycosis requires long-term systemic therapy, it is essential to diagnose the infection accurately. Although in theory this diagnosis sho uld be simple, results achieved in practice are uneven. Clinicians should b e aware of the need to collect an adequate specimen and of the possible nee d for repeat collections. Direct microscopic techniques for examination of nail scrapings include 10% potassium hydroxide (KOH) with Parker ink, 10% K OH with dimethyl sulfoxide, and 10% KOH with Calcofluor white. When interpr eting fungal culture results, it should be noted that negative results are frequent and that contaminant yeasts and molds are common, but that nonderm atophytes such as Candida, Scopulariopsis, and Scytalidium can infrequently cause onychompcosis.