Multiplex RT-PCR provides improved diagnosis of skin and nail dermatophyte infections compared to microscopy and culture: a laboratory study and review of the literature

Dermatophytes are the most common cause of superficial mycosis, estimated to affect 20% to 25% of the general population. We assessed the performance of a novel real-time polymerase chain reaction (RT-PCR) multiplex assay for diagnosis of dermatophytosis. To evaluate sensitivity and specificity, 10 known bacteria and 10 known fungi commonly found on skin, as well as 105 samples with culture confirmed dermatophytosis were tested using Dermatophyte and Fungi assay (AusDiagnostics, Sydney, Australia), a novel multiplex assay for diagnosis of dermatophytosis in skin and nail. This was followed by prospective evaluation of 195 clinical samples for dermatophytosis by both conventional methods and RT-PCR. RT-PCR showed almost two-fold higher sensitivity and high specificity in the diagnosis of skin and nail dermatophytosis compared to traditional microscopy and culture. In addition, RT-PCR demonstrated markedly reduced turnaround time from 4 to 6 weeks to 4 to 6 hours and ability for high throughput.