Detection of common dermatophytes in clinical specimens using a simple quantitative real‐time TaqMan polymerase chain reaction assay. (18th November 2015)

• Record Type: Journal Article
• Authors: Ohst, T.; Kupsch, C.; Gräser, Y.
• Is Part Of: British journal of dermatology. Volume 174:Number 3(2016)
• Page Start: 602
• Page End: 609
• Publication Date: 2015-11-18
• Subjects: Dermatology -- Periodicals; Skin -- Diseases -- Periodicals; 616.5
• DOI: 10.1111/bjd.14198
• Languages: English
• ISSNs: 0007-0963

Abstract

Summary: Background: 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. Objectives: 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. Methods: 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. Results: 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 ). Conclusions: The qRT‐PCR assay developed in this study allows the specific and sensitive detection of relevant dermatophytes at low cost in a short time. Abstract : What's already known about this topic? Quantitative real‐time polymerase chain reaction (qRT‐PCR) is a useful tool for routine diagnosis of dermatophyte species, as it requires no time‐consuming and contamination‐susceptible post‐PCR procedures. qRT‐PCR is expensive due to the requirement of fluorescent labels. What does this study add? The qRT‐PCR method developed in this study is based on a singleplex approach. This method (i) minimizes the amount of fluorescence‐labelled probes per reaction, making the procedure more cost‐efficient; (ii) prevents competitions of primers and thus reduction of sensitivity; and (iii) makes the expansion of the test platform to additional species easy. This is the first qRT‐PCR that includes both a pan‐dermatophyte reaction and specific reactions for the detection of relevant pathogenic dermatophytes. Linked Comment: Hay. Br J Dermatol 2016;174: 483–484 .