Yeast Species in the Oral Cavities of Older People

Abstract

Oral candidiasis is prevalent among older people due to predisposing factors such as impaired immune defences, medications and denture use. An increasing number of older people live in rest home facilities and it is unclear how this institutionalised living affects the quantity and type of fungi colonizing these people’s oral cavities. Smears and swabs of the palate and tongue, and saliva samples were taken from participants residing in rest homes (RH; n = 25) and older people living in their own homes (OH; n = 25). Yeast in samples were quantified and presumptively identified by culturing on CHROMagar Candida agar. Sequencing of the ITS2 region of rDNA was carried out to confirm yeast species. Multilocus sequence typing (MLST) of 7 housekeeping genes was used to compare Candida albicans strains. A higher proportion of RH residents had Candida hyphae present in smears compared to OH participants (35% vs. 30%) although this difference was not statistically significant (p = 0.74). RH residents had, on average, 23 times as many yeast per mL saliva as OH participants (p = 0.01). C. albicans and C. glabrata were the most common species isolated from both participant groups. All C. albicans strains were similar within the same participant but very different between participants. Nine strains, found in 4 rest home participants, appeared to be C. albicans/Candida dubliniensis chimeras (hybrid strains). The results indicate that communal living for those who reside in an age care facility has an impact on the abundance of yeast species and the prevalence of chimera strains. This may be due to morbidities which led to the need for residential care and/or related to the rest home environment.