Direct detection and differentiation of causative fungi of onychomycosis by multiplex polymerase chain reaction-based assay.

A rapid and reliable triplex PCR procedure was developed to detect pathogenic fungi directly from specimens of onychomycosis. One hundred and four patients were included in this study. Of them, forty-five (43.3%) were finally diagnosed with onychomycosis according to the diagnostic criteria. The sensitivity of PCR, microscopy and culture were 93.3%, 100% and 64.4%, respectively; the specificities were 100%, 86.4% and 100%, respectively; the positive predictive values were 100%, 84.9% and 100%, respectively; the negative predictive values were 95.2%, 100% and 78.7%, respectively. This molecular diagnostic process could distinguish the 3 groups of pathogens in onychomycosis (dermatophyte, yeast and mold) and could be completed within 8 h. This multiplex PCR assay could used in laboratories with no mycological specialization for rapid etiologic diagnosis and treatment selection, especially in suspected fungus cases if they can not be detected by conventional methods or if a rapid diagnosis of onychomycosis is needed.