Precision diagnostics in paediatric dermatology: Advancing management of tinea capitis through dermatophyte PCR

Tinea capitis (TC) is the most frequent dermatophyte infection in children requiring systemic and topical treatment for several weeks. Traditionally, diagnosis and treatment monitoring were based on microscopic examination and fungal culture of scales and plucked hairs, which both have significant limitations.

To investigate the role of dermatophyte polymerase chain reaction (PCR) in the treatment of TC.

Scales and plucked hairs of children with TC were investigated by dermatophyte PCR, microscopic examination and fungal culture at baseline and during antifungal treatment.

Seventeen children with TC were included. At baseline, sensitivity of PCR was 100% as compared to 60% and 87% for direct microscopy and fungal culture, respectively. Species identification by PCR and fungal culture was consistent in all cases. During follow-up, analysis of 38 samples under treatment showed a sensitivity of PCR, direct microscopy and fungal culture of 68%, 26% and 89% while specificity was 84%, 100% and 100%, respectively. PCR during therapy proved to be false-negative in six and false-positive in three instances. The latter turned negative after 4 weeks without further systemic treatment.

Dermatophyte PCR is an excellent tool for baseline diagnostics of TC providing rapid and accurate results. Our findings suggest that due to the fast and reliable results, it may replace direct microscopy and fungal culture to confirm or exclude TC in children. In the treatment course, diagnostic accuracy and performance of PCR seem reduced as compared to fungal culture, limiting its value for treatment monitoring. Mycological cure ascertained by fungal culture should currently remain the therapeutic goal.