Mycoses. 2017;1–5. wileyonlinelibrary.com/journal/myc | 1 © 2017 Blackwell Verlag GmbH Received: 10 March 2017 | Revised: 25 May 2017 | Accepted: 29 May 2017 DOI: 10.1111/myc.12648 ORIGINAL ARTICLE Clinical evaluation of β-tubulin real-time PCR for rapid diagnosis of dermatophytosis, a comparison with mycological methods Marjan Motamedi 1,2 | Hossein Mirhendi 3 | Kamiar Zomorodian 1 | Hossein Khodadadi 1 | Mahboobeh Kharazi 4 | Zeinab Ghasemi 2 | Mohammad Reza Shidfar 2 | Koichi Makimura 5 1 Department of Medical Parasitology and Mycology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran 2 Department of Medical Parasitology and Mycology, School of Public Health, National Institute of Health Research, Tehran University of Medical Sciences, Tehran, Iran 3 Department of Medical Parasitology and Mycology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran 4 Department of Medical Parasitology and Mycology, International Campus, Tehran University of Medical Sciences, Tehran, Iran 5 Laboratory of Space and Environmental Medicine, Graduate School of Medicine, Teikyo University, Tokyo, Japan Correspondence Hossein Mirhendi, Department of Medical Parasitology and Mycology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran. Email: mirhendi@tums.ac.ir Funding information Tehran University of Medical Sciences (TUMS) Summary Following our previous report on evaluation of the beta tubulin real-time PCR for de- tection of dermatophytosis, this study aimed to compare the real-time PCR assay with conventional methods for the clinical assessment of its diagnostic performance. Samples from a total of 853 patients with suspected dermatophyte lesions were sub- jected to direct examination (all samples), culture (499 samples) and real-time PCR (all samples). Fungal DNA was extracted directly from clinical samples using a conical steel bullet, followed by purification with a commercial kit and subjected to the Taq-Man probe-based real-time PCR. The study showed that among the 499 specimens for which all three methods were used, 156 (31.2%), 128 (25.6%) and 205 (41.0%) were found to be positive by direct microscopy, culture and real-time PCR respectively. Real-time PCR significantly increased the detection rate of dermatophytes compared with microscopy (288 vs 229) with 87% concordance between the two methods. The sensitivity, specificity, positive predictive value, and negative predictive value of the real-time PCR was 87.5%, 85%, 66.5% and 95.2% respectively. Although real-time PCR performed better on skin than on nail samples, it should not yet fully replace conventional diagnosis. KEYWORDS beta-tubulin gene, dermatophyte, diagnosis, real-time PCR 1 | INTRODUCTION Superficial fungal infections are common diseases, affecting millions of people worldwide. 1 They occur in both immunocompetent and im- munocompromised individuals, and the etiological agents comprise dermatophytes, yeast and non-dermatophyte molds. 2 Dermatophytes, including the anamorphic (asexual) genera Epidermophyton, Microsporum and Trichophyton, are a group of ke- ratinophilic molds that may infect skin, nails, and hair. These genera are responsible for most superficial fungal infections, and the esti- mated lifetime risk of acquiring a dermatophyte infection is between 10%-20%. 3 As an example, tinea pedis and tinea unguium are the most frequent types of dermatophytosis 4 and were found in 1474 and 818 of 8804 patients in Japan (16.7% and 9.3%) respectively, with symp- toms “other than athlete’s foot.” 5 Tinea unguium has a prevalence of at least 12.4% in the general population of Europe; 6 in older individuals, it is as high as 20%. 7 Standard methods for laboratory diagnosis of dermatophytosis include direct microscopic examination and culture of clinical spec- imens. 8 Direct microscopy is rapid and inexpensive; however, its sensitivity is dependent on several factors including the skill of the op- erator and the quality and quantity of nail samples obtained; besides,