Rapid detection of dermatophytes from skin and hair

Abstract

BackgroundDermatophytes are a group of closely related keratinophilic fungi that can invade keratinized humans and animals tissues such as skin, hair and nails causing dermatophytosis. They are an important cause of superficial fungal infection.FindingsConventional methods like potassium hydroxide (KOH) microscopy and fungal culture lacks the ability to make an early and specific diagnosis. In this study we have evaluated nested Polymerase chain reaction (PCR) using primers targeting dermatophyte specific sequence of chitin synthase 1 (CHS1) gene and compared with conventional test. A total of 155 patients clinically suspected with dermatophytosis were included in the study. Of which 105 specimens were skin scrapings and 50 were hair. KOH microscopy, fungal culture and first round and nested PCR were done on clinical specimens, and results compared. Nested PCR for dermatophytes was positive in 83.8% specimens, followed by KOH microscopy (70%), first round PCR (50.8) and fungal culture (25.8).ConclusionResults indicate that nested PCR may be considered as gold standard for the diagnosis of dermatophytosis and can aid the clinician in initiating prompt and appropriate antifungal therapy.

Genotyping and Molecular Characterization of Dermatophytes Isolates Collected from Clinical Samples

“…KOH microscopy has low specifi city and fungal culture can identify specifi c pathogen but it takes a long incubation period [21]. The false negative rate of fungal culture is approximately 30% and the sensitivity was about 60% [20].…”

“…Further it is more diffi cult to diagnose dermatophytosis in immunocompromised patients; since clinical presentation is often atypical [20]. The differential diagnosis of dermatophytoses includes seborrhoeic dermatitis, atopic dermatitis, contact dermatitis, psoriasis, candidal intertrigo, erythrasma, Eczema etc [21].…”

“…They are classifi ed in three anamorphic genera: Epidermophyton, Microsporum and Trichophyton [1]. Dermatophytes are responsible for most superfi cial fungal infections and the estimated lifetime risk of acquiring a dermatophyte infection is between 10-20% [2].…”

The Use of Polymerase Chain Reaction in Laboratory Diagnosis of Dermatophytosis

“…mentagrophytes'e özgül nPCR arasında iyi düzeyde (κ= 0.78), pan-dermatofi t nPCR ile T.rubrum/T.mentagrophytes'e özgül nPCR arasında mükemmel düzeyde uyum bulunmuştur (κ= 0.93). Hat 4,5,[7][8][9][10]12,16,19,21: Negatif örnekler; Hat 6,11,[13][14][15]17,18,20, …”

“…Meriç ve arkadaşlarının 12 çalışması dışındaki çalışmalarda [14][15][16] , bizim çalışmamızda olduğu gibi mantarların DMİ'de saptanma oranları, kültürde üreme oranlarına göre daha yüksektir. Bu durum, örnekte mantar yapılarının az sayıda bulunması veya hifl erin canlılığını yitirmiş olması ile açıklanabilmektedir 9,17 . Dermatofi tlerin laboratuvar tanısında rutinde kullanılan yöntemler olan DMİ ve mantar kültürünün olumsuz yanlarının bulunması nedeniyle yeni testlere ihtiyaç duyulmaktadır.…”