MICROEVOLUTION OF CANDIDA ALBICANS STRAINS IN OLDER PEOPLE WITH LOW SALIVARY FLOW

Abstract

Background Populations are aging worldwide, and older people are more likely to take medications and undergo treatment leading to side effects such as salivary gland hypofunction. It is not known how reduced salivary flow in older people affects the Candida albicans strains colonizing the oral cavity. The presence of resistant Candida strains could be debilitating for immunocompromised older people. Objective The aim of this study was to compare C. albicans strains colonizing the mouths of older people with low and normal salivary flow. Methods Participants aged 65 and above (n = 50) were examined, and their salivary flow rates (SFRs) were determined. Swabs and smears of the palate and tongue and saliva samples were collected. Smear products were stained with periodic acid-Schiff (PAS). Yeasts were cultured, quantified, and presumptively identified using CHROMagar Candida agar. Multilocus sequence typing was used to compare C. albicans strains. Results Twenty-four participants had a low SFR ( 400 CFU/mL saliva) (68% vs 38%), presented with more PAS-positive smears (47% vs 19%), and had more C. albicans strains with evidence of microevolution (8 of 12 participants vs 1 of 5 participants) than those with normal salivary flow. Conclusions Increased yeast presence in older people with low salivary flow was confirmed. There was a link between SFR and microevolution of C. albicans. The genetic changes may be because C. albicans is under pressure to adapt to a low-saliva environment.