Detection of dermatophytes by polymerase chain reaction

A polymerase chain reaction (PCR) assay for the detection of dermatophytes was established. The primers ''TRl'' and ''TR2'' amplify a 581 bp fragment within the gene coding for the small ribosomal subunit (18S rRNA) of fungi. PCR allowed the detection of isolates of 7 common dermatophytes and in addition several yeasts and moulds. Hybridisation with specific oligonucleotides results in the identification of dermatophytes and Candida albicans. Restriction analysis of the PCR product allowed us to distinguish between dermatophytes and yeasts or moulds. The specifity of the PCR with respect to fungi was assessed by testing human DNA collected from 42 dermis and epidermis specimens as well as DNA from selected plants and animals. To evaluate the clinical relevance of the PCR as say, 69 routinely collected skin and nail specimens were examined by PCR and culture. PCR detected dermatophytes in 35 and culture in 28 of 38 specimens that were classified as positive. Sensitivity of PCR (92%) was higher than that of culture (73%). These results show that PCR has advantages over culture for the detection of dermatophytes.