Detection of common dermatophytes in clinical specimens using a simple quantitative real-time TaqMan polymerase chain reaction assay.

Abstract

Dermatophytes are common fungal pathogens causing mostly superficial infections in humans with a high prevalence worldwide. Traditional detection techniques are time-consuming and insensitive, whereas molecular detection methods have proved to be much more rapid and sensitive. To develop a modular singleplex quantitative real-time polymerase chain reaction (qRT-PCR) assay for the detection of the most common dermatophytes in clinical specimens. The qRT-PCR assay is based on single-tube reactions with TaqMan probes. We validated the test with 311 clinical samples of human and animal origin submitted for routine diagnosis and compared the qRT-PCR results with microscopy and culture. qRT-PCR proved to be significantly more sensitive than microscopy and culture, with 21·2% more positive samples. Among the 201 dermatophytes identified 152 were Trichophyton rubrum (75·6%) and 34 were Trichophyton interdigitale (16·9%). Only 15 samples were determined as less common dermatophytes (Microsporum canis, Epidermophyton floccosum, Trichophyton verrucosum and Arthroderma benhamiae). In the present study, pathogen identification was achieved for 95·2% of all samples (including negatives) by applying only three detection tests (pan-dermatophyte, T.rubrum and T.interdigitale). The qRT-PCR assay developed in this study allows the specific and sensitive detection of relevant dermatophytes at low cost in a short time.