Funding sources This work was partially supported by the Swiss National Foundation for Scientific Research, grant CRSII3_127187.
Clinical and Laboratory Investigations
Dermatophyte identification in skin and hair samples using a simple and reliable nested polymerase chain reaction assay
Article first published online: 30 JAN 2013
© 2012 The Authors. BJD © 2012 British Association of Dermatologists
British Journal of Dermatology
Volume 168, Issue 2, pages 295–301, February 2013
How to Cite
Verrier, J., Krähenbühl, L., Bontems, O., Fratti, M., Salamin, K. and Monod, M. (2013), Dermatophyte identification in skin and hair samples using a simple and reliable nested polymerase chain reaction assay. British Journal of Dermatology, 168: 295–301. doi: 10.1111/bjd.12015
Conflicts of interest None declared.
- Issue published online: 30 JAN 2013
- Article first published online: 30 JAN 2013
- Accepted manuscript online: 22 AUG 2012 09:41AM EST
- Accepted for publication 14 August 2012
Summary Background Dermatophyte identification in tinea capitis is essential for choosing the appropriate treatment and in tinea infections to identify the possible source. The failure of fungi to grow in cultures frequently occurs, especially in cases of previous antifungal therapy.
Objectives To develop a rapid polymerase chain reaction (PCR) sequencing assay for dermatophyte identification in tinea capitis and tinea corporis.
Material and methods Fungal DNA was extracted from hair and skin samples that were confirmed to be positive by direct mycological examination. Dermatophytes were identified by the sequence of a 28S ribosomal DNA subunit amplicon generated by nested PCR.
Results Nested PCR was found to be necessary to obtain amplicons in substantial amounts for dermatophyte identification by sequencing. The results agreed with those of classical mycological identification in 14 of 23, 6 of 10, and 20 of 23 cases of tinea capitis, tinea corporis and tinea pedis, respectively, from which a dermatophyte was obtained in culture. In seven of the 56 cases, another dermatophyte was identified, revealing previous misidentification. A dermatophyte was identified in 12 of 18, three of five, and four of nine cases of tinea capitis, tinea corporis and tinea pedis, respectively, in cases in which no dermatophyte grew in culture.
Conclusions Although the gold standard dermatophyte identification from clinical samples remains fungal cultures, the assay developed in the present study is especially suitable for tinea capitis. Improved sensitivity for the identification of dermatophyte species was obtained as it is possible to identify the dermatophyte when the fungus fails to grow in cultures.