Polymerase Chain Reaction-Restriction Fragment Length Polymorphism for Characterization of Candida Species Causing Onychomycosis

Traditional methods that are used to identify clinical isolates of Candida species are time-consuming and not appropriate for rapid, accurate and reliable identification. The aim of this study was to characterize Candida species isolated from fingernail onychomycosis by using polymerase chain reaction (PCR) followed by restriction fragment length polymorphism (RFLP) with three different restriction enzymes HaeIII, DdeI and BfaI. Sixteen Candida isolates recovered from infected fingernail samples were selected and phenotypically identified by API 20C identification kit. Also, the five species were identified genotypically with PCR-RFLP analysis. Sixteen clinical Candida isolates comprising five species were included in this study, three Candida species were identified using conventional API 20C: C. albicans (9/16), C. parapsilosis (3/16) and C. glabrata (1/16) with three unidentified isolates. Five species were identified based on genotypic identification with PCR-RFLP analysis revealing C. albicans (9/16), C. parapsilosis (4/16), C. glabrata, C. guilliermondii and C. tropicalis (1/16 for each). It was concluded that the PCR-RFLP analysis of rDNA enabled more easy, rapid and precise identification of Candida species comparing to phenotypic methods. RFLP analysis demonstrated that HaeIII is the most differentiating enzyme that distinguished C. albicans from non C. albicans species. BfaI maintained the differentiation of these non C. albicans species and DdeI digestion confirmed C. albicans species.