Distribution of Yeast Species and Risk Factors of Oral Colonization among the Residents at Nursing Homes in Taiwan

Introduction: Candida species are part of commensal microflora and etiological agents of different infections in humans. Fungal infections contribute to approximately one million deaths annually. Objective: The present study is to determine the distribution of yeast species and the risk factors of yeast colonization in the oral cavities of residents at 10 nursing homes in Taiwan. Methods: Oral rinses of residents were collected. All yeast isolates were subjected to the matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) for species identification. The sequences of the internal transcribed spacer (ITS) region and/or the D1/D2 region of ribosomal DNA were used for assessing species identification. Results: Among 158 of 204 residents colonized by yeasts, 52 were colonized by Candida albicans alone and 106 were colonized by at least one non-C. albicans yeast species. Interestingly, 88 of the 158 subjects were colonized by more than one species. Among the 320 isolates, comprising 12 fungal genera and 33 species, C. albicans (40.3%) was the dominant species, followed by C. glabrata (15.9%), C. parapsilosis (10.6%), C. tropicalis (6.9%), and Trichosporon asahii (5.6%). Age, chewing betel nuts, having dentures, periodontal disease, or other chronic diseases are expected risk factors for being colonized by yeast. Interestingly, we also identified two less expected risk factors: being female and brushing teeth more than once a day. Furthermore, residents colonized by > 10 colony-forming unit (CFU) of yeast (OR, 6.156; 95% CI 2.709–13.989; p = 0.001) or age > 70 years (OR, 2.435; 95% CI 1.057–5.607; p = 0.037) were independent factors associated with multi-species colonization. ©2019 The Authors. Published by the JScholar under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/ by/3.0/, which permits unrestricted use, provided the original author and source are credited. J Dent Oral Health 2019 | Vol 6: 301