The effect of six-weeks advanced oral care on oral microbiome and mycobiome composition in people with dementia living in aged-care facilities

Oral health is an important aspect of quality of life for elderly people, especially with those with dementia. The impact of an active oral hygiene program on oral bacterial and fungal communities was tested in a group of elderly participants with dementia tested against a separate control group whose oral hygiene followed the staus quo. These groups lived in separate aged care facilities and had an average age of 84. The oral cavity microbiomes and mycobiomes were assessed from swabs of cheek, gum and tongue surfaces. Samples were collected at the beginning and at the completion of the 6 week study period and bacterial and fungal community profiles were determined by short read metabarcode sequencing of 16S rRNA (V3-V4 region) genes and rRNA operon ITS1/ITS2 regions, respectively. Minor reductions in bacterial species richness was observed but this was found to occur in both control and experimental groups. The implementation of a more intensive and structured oral hygiene did not affect either bacterial or fungal taxa distributions. Most of the bacterial and fungal dataset variations were due to differences between participants and interactions with other factors (70 to 78% of the variance) while the specific effect of the experimental design only explained about 2% of the total variance. In the case of the mycobiome data oral sampling sites was more influential in comparison to bacterial communities where the distribution across sites was relatively homogenous. Conclusively, the instigation of a more vigorous oral hygiene had no measurable impact on either the richness or structure of microbiomes or mycobiomes of the elderly participants. To enable an alteration of oral cavity communities that may improve overall oral health and mitigate infectious disease risks in the elderly more targeted and specific hygiene approaches seem to be required for the purposes for assessing effectiveness at the microbiological level.