Abstract
To understand the pathogenicity and clinical significance of dermatophytes (also known as ringworms), the correct identification of these molds is essential. However, in routine practice they are notoriously difficult to classify and identify. The morphology of macroconidia, which are abundantly produced under suitable in vitro conditions, have provided useful criteria for the identification of many of the dermatophytes. However, several of them, including Microsporum audouinii, M. ferrugineum, Trichophyton concentricum, T. schoenleinii, T. verrucosum, and T. violaceum (including T. soudanense and T. yaoundei) rarely produce macroconidia and cannot be easily identified. The objective of this study was to design, optimize, and evaluate real-time PCR as a tool for identifying dermatophytic fungi in a laboratory setting. The performance of the assay was evaluated using 64 dermatophyte isolates, i.e., 35 rare macroconidia-producing reference strains, including the six species mentioned above, and 29 clinical isolates from our laboratory, including M. canis (4), T. mentagrophytes (2), T. rubrum (20), T. rubrum with the ‘raubitschekii’ morphotype (2), and T. tonsurans (1). Real-time PCR correctly identified 10 taxonomically distinct dermatophytes, particularly rare macroconidia-producing species, with excellent sensitivity (100%). The advantages of the assay include the provision of accurate and reliable diagnoses of dermatophytic fungi.
Acknowledgements
This study was supported by the Research Fund of Çukurova University (projects no: TF2009YL19 and TF2010BAP22). We express gratitude to the curators of the Centraalbureau voor Schimmelcultures (Utrecht, The Netherlands) for kindly providing the dermatophyte isolates. We also thank Mr Mehmet Kurul for providing technical assistance during this study. In addition, we appreciate and give our sincere thanks to two anonymous reviewers for their critical comments on earlier drafts of this paper.
Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.
This paper was first published online on Early Online on 27 September 2011.