A Pilot Study for the Evaluation of PCR as a Diagnostic Tool in Patients with Suspected Dermatophytoses

The conventional diagnostic tools for dermatophytoses suffer from several limitations including low sensitivity, specificity, and long turn-around-time.

The present study was, therefore, performed to evaluate the performance of a polymerase chain reaction (PCR)-based method for the diagnosis of this condition.

The study was conducted in the Dermatology outpatient department of a tertiary care teaching hospital in central India over a period of 3 months from July to September 2015.

Forty participants, including 25 cases and 15 controls, were recruited in this observational study. Direct microscopy and fungal culture were performed from skin scrapings and nail clippings collected from the participants. PCR was also performed to amplify the chitin synthase 1 and internal transcribed spacer 2 genes from DNA samples extracted from the same clinical materials, using the method reported by Brillowska-Dabrowska et al. The diagnostic performance of fungal culture and PCR was compared using OpenEpi software.

We observed a significant male predominance among patients with dermatophytoses. The sensitivity of fungal culture and dermatophyte PCR to diagnose dermatophytoses was 24% and 48%, respectively, whereas the specificity of the two assays was 100% and 93.3%, respectively. The likelihood ratio of a positive PCR assay was 7.2 and the negative likelihood ratio was 0.5. PCR assay also delivered a significant shortening of the time-to-diagnosis, with the mean turn-around-time being 8 hours and 14 days for PCR and culture, respectively.

This study, thus, highlights the potential merits of the dermatophyte PCR assay in achieving a rapid diagnosis of dermatophytoses and underscores its utility as a complementary test to improve the sensitivity of the conventional diagnostic tools for this condition, as well as to reliably differentiate this condition from other similar skin conditions.