In accordance with progression in mycological diagnostic approaches, today there are two diagnostic categories including traditional and advanced molecular diagnostic tools available. Accuracy, availability, rapidity, sensitivity, specificity and cost effectiveness are important items for diagnostic procedures. Nevertheless, routine traditional diagnostic tools are not able to warrant adequate sensitivity and specificity (62).
Traditional diagnostic techniques
Traditional mycological diagnostics involve specimen direct microscopy, Wood’s lamp test, fungal culture medium, and biopsy. (2, 5, 63, 64).
Specimen direct microscopy
Direct microscopic observation of fungi in clinical samples is obviously a cheap and short-time diagnostic method. Clinical specimen must be prepared by scalpel, moving to a clean glass slide with a drop of 10%-20% KOH. Mild heat may help to increase the lytic activity of KOH on fungal α-(1,3) and α-(1,4) cross linkages in cell wall glucan polymers to have a clear and transparent vision of dermatophyte fungal elements including filamentous, septate, and branched hyphae with or without conidia among the specimen (1-3, 8, 9, 17, 65).
Providing suitable samples is an important part of direct microscopy. Accuracy in isolation of scale from peripheral border of suspected lesion, obtaining infected hair shafts or hair follicles, scraping from infected nails are the primary procedures for preparing valuable samples to have a successful observation to confirm the presence or absence of dermatophyte fungi. According to previous studies, sensitivity and the specificity of direct KOH microscopy are ~65% and >45% (1, 2, 8, 17, 66, 67).
Wood’s lamp test
Wood’s lamp tool is a limited diagnostic method which can be used for detecting Tinea capitis caused by fluorescent metabolite producing dermatophyte of M.canis (fluorescence blue-green) and M.audouinii (fluorescence grey-yellow) in a dark room (1, 2, 8, 53, 68).
Fungal culture medium
Culture is an expensive and time consuming technique with low sensitivity (30%-35%) and higher specificity. In mycological methodology, it is important to have adequate amounts of samples to increase the accuracy of results. In traditional diagnostics, clinical samples including scale, hair and nail scraping must be used simultaneously for direct microscopy and culture medium. For positive result of culture technique usually takes two weeks while a negative result of culture method normally needs a period of 6 weeks. Sabouraud Dextrose Agar (SDA) is recommended for the most in culture medium technique (1, 2, 8, 17, 63, 64).
Biopsy from nail or skin is used when the clinical manifestations of dermatophytosis are present but results of direct microscopy and culture are negative or even treatment did not responded to ring worm (2, 8).
Advanced molecular tools
Advanced molecular diagnostics provide successful approaches for rapid diagnosis of pathogenic dermatophytes with...