Onychomycosis is the most common nail disorder, accounting for up to 50% of all nail
problems and about 30% of cutaneous fungal infections. Treatment of onychomycosis is expensive.
It requires long-term therapy with an oral antifungal medication with potential side effects.
Therefore, a proper diagnosis of infection is needed. Aim of the study: This study aimed to compare
real time PCR using novel primers targeting the pan-dermatophyte-specific sequence of the chitin
synthase 1 gene (CHS1) with nested PCR targeting the same gene, KOH microscopy, direct microscopy
in relation to culture for diagnosis of clinically suspected onychomycosis.
Subjects and methods: This study was conducted during the period from April 2013 through May
2014. Eighty patients attending Outpatient Dermatology and Andrology clinic at Benha University
Hospital were included in this study. They were 30 females and 50 males with suspected clinical
diagnosis of onychomycosis. Their ages ranged from 22 to 77 years. Thirty eight of them were living
in rural areas, while the other 42 came from urban areas. Nail scrapings were collected and
examined by the following: direct KOH microscopic examination, culture, nested PCR using double
sets of primers and finally real time PCR. Results: As regards direct microscopy by KOH
examination, 66 (82.50%) cases were positive, while 14 (17.5%) were negative. Culture was positive
only in 38 (47.5%) of nail samples revealing different fungi. Dermatophytes were isolated from 30
(37.5%) cases; most of them were Trichophyton mentagrophytes, and in 8 cases the only isolatednon-dermatophytic organism was Aspergillus Niger spp. (10.00%). Nested PCR was positive in 52
(65.00%) of nail samples while real time PCR was positive in 58 (72.5%) of nail samples.
Conclusion: Real-time PCR followed by melting-point analysis, gives a diagnostic tool that has a
higher sensitivity (93.3%) and is faster than nested PCR (73.3%) and other conventional methods. |
