Molecular Identification and Phylogenetic Characterization of Yeast Species Isolated from Complete Denture in Sulaymaniyah, Iraq

The increasing prevalence of oral fungal infections, particularly among denture wearers, underscores the need for accurate species identification. To investigate the prevalence and diversity of yeast species colonizing dentures. Oral swabs from denture surfaces were collected from 100 participants at the Peramerd Dental Center, Sulaymaniyah, Iraq, from September to November 2024. Samples were cultured on chromogenic media, and yeast isolates were identified and sequenced. Then, phylogenetic analysis was performed using the Neighbour-Joining method. <i>Candida albicans</i> was the most prevalent isolated species among patients with denatured samples (46%). However, 54% of isolates comprised other yeast species, including <i>Kluyveromyces marxianus</i> and <i>Candida tropicalis</i> (each at 8%), <i>Nakaseomyces glabrata</i> (6%), <i>Meyerozyma guilliermondii</i> (4%), <i>Pichia kudriavzevii</i>, and <i>Candida dubliniensis</i> (each at 2%). Notably, <i>Pichia ethanolica</i>, which is not typically considered part of the human mycobiome, was identified in two cases, including one instance of co-isolation with <i>C. albicans</i>. This study is the first to detect <i>P. ethanolica</i> on the denture surface used by the patients. Phylogenetic analysis confirmed species-level identity and genetic distinctiveness of both <i>Candida</i> and non-<i>Candida</i> isolates. These findings highlight the evolving diversity of oral mycobiota in denture wearers and the importance of molecular diagnostics in managing fungal infections. The high proportion of non-<i>Candida</i> species and the identification of <i>P. ethanolica</i> underscore the complex and potentially shifting fungal ecology associated with denture use, with implications for antifungal treatment strategies, and the need for further investigation into the origins and relevance of rare fungal species in the oral cavity.