Identification of Candida spp. in denture wearers by two amplicon-based molecular typing techniques

Although molecular methods such as quantitative Polymerase Chain Reaction with High-Resolution Melting Curve (qPCR-HRMC) analysis and Restriction Fragment Length Polymorphism (PCR-RFLP) enable accurate identification of Candida spp., their application to denture samples remains limited. This study applied qPCR-HRMC and PCR-RFLP to identify Candida species in denture wearers with and without denture stomatitis.

Biofilm samples from denture wearers with and without denture stomatitis (n = 40) were collected using swabs and ultrasound, followed by DNA extraction and qPCR-HRMC for direct Candida identification. All samples were cultured on CHROMagar Candida for presumptive identification. When direct identification was not possible, cultured isolates were subjected to qPCR-HRMC. For PCR-RFLP, purified amplicons were digested with a restriction enzyme, and electrophoretic banding patterns were compared with reference strains. Cohen's kappa coefficient (κ) evaluated the agreement between qPCR-HRMC and CHROMagar Candida.

qPCR-HRMC successfully identified Candida albicans and Candida tropicalis directly from denture biofilms colonized by a single species. In contrast, identification of Nakaseomyces glabratus, Candida dubliniensis, and mixed-species colonization required prior cultivation. Substantial agreement was observed between CHROMagar™ Candida and qPCR-HRMC (κ = 0.826), with 100% sensitivity for C. albicans and high specificity for N. glabratus (97%) and C. tropicalis (100%). PCR-RFLP showed limited discriminatory capacity.

qPCR-HRMC proved effective for the direct detection of C. albicans and C. tropicalis in denture biofilms, whereas identification of other species and mixed-species colonization required prior cultivation. PCR-RFLP was not suitable for Candida identification in these samples.