Biocultural Drivers of Salivary Microbiota in Australian Aboriginal and Torres Strait Islander Children

Abstract

Australian Aboriginal and Torres Strait Islander children experience unacceptably high rates of dental caries compared to their non-Indigenous Australian counterparts. Dental caries significantly impacts the quality of life of children and their families, particularly in remote communities. While many socioeconomic and lifestyle factors impact caries risk, the central role of the oral microbiota in mediating dental caries has not been extensively investigated in these communities. Here, we examine factors that shape diversity and composition of the salivary microbiota in Aboriginal and Torres Strait Islander children and adolescents living in the remote Northern Peninsula Area (NPA) of Far North Queensland. We employed 16S ribosomal RNA amplicon sequencing to profile bacteria present in saliva collected from 205 individuals aged 4–17 years from the NPA. Higher average microbial diversity was generally linked to increased age and salivary pH, less frequent toothbrushing, and proxies for lower socioeconomic status (SES). Differences in microbial composition were significantly related to age, salivary pH, SES proxies, and active dental caries. Notably, a feature classified as Streptococcus sobrinus increased in abundance in children who reported less frequent tooth brushing. A specific Veillonella feature was associated with caries presence, while features classified as Actinobacillus/Haemophilus and Leptotrichia were associated with absence of caries; a Lactobacillus gasseri feature increased in abundance in severe caries. Finally, we statistically assessed the interplay between dental caries and caries risk factors in shaping the oral microbiota. These data provide a detailed understanding of biological, behavioral, and socioeconomic factors that shape the oral microbiota and may underpin caries development in this group. This information can be used in the future to improve tailored caries prevention and management options for Australian Aboriginal and Torres Strait Islander children and communities.

First insight into oral microbiome diversity in Papua New Guineans reveals a specific regional signature

“…These files were merged with our data set to perform beta‐diversity analysis and to calculate the abundances of the core microbiome. For the Australian Aboriginals and Torres Strait Islanders (Handsley‐Davis et al, 2021) and the Batwa Pygmies populations (Nasidze et al, 2011), we were not able to obtain WGS raw data, as they only sequenced a region of the microbial 16S rRNA gene (V4 for the Australian Aboriginals and Torres Strait Islanders and V1 and V2 for the Batwa pygmies). For these, we retrieved the values of abundance for the core microbiome that were described and available in their publications.…”

“…The null hypothesis tested by PERMANOVA was that the centroids of each group are equivalent, under the assumption of exchangeability of the samples among groups.Comparative analysis of oral microbiome data from other populationsThe qualitative results (Microbiome array) were used to perform the analysis of the PNG oral microbiome (Alpha-diversity) as we have more available samples. To have a global perspective of the oral microbiome of PNG populations in the global oral microbiome we compared the abundance of the core microbiome obtained from the quantitative results (WGS) in this study with other published studies for Philippines hunter-gatherers and farmers, Batwa Pygmies, Aboriginal Australians and Westernized individuals (Handsley-Davis et al, 2021;Lassalle et al, 2018;Nasidze et al, 2011). For the hunter-gatherers and traditional farmer groups from the Philippines and their curated data of the Western controls from the Human Microbiome Project(Lassalle et al, 2018), we downloaded their published microbial metagenomic read data sets from ENA (www.ebi.ac.uk/ena; BioSample Accession nos.…”

Predicting dental caries increment using salivary biomarkers in a remote Indigenous Australian child population

“…This is consistent with our baseline study where caries experience was approximately twice in those with higher counts of salivary MS than in those with lower counts [34], demonstrating that simple chair side assessment of MS would assist in determining the risk for future caries. This remains true even though we now recognise that a cariogenic/acidogenic microbiome can vary considerably and there is nothing highly specific about mutans Streptococci [35][36][37][38]. It is not surprising that our interventions designed to reduce total oral bacterial loads were found to be effective in preventing dental caries in this community [39].…”

Heritage-specific oral microbiota in Indigenous Australian dental calculus

“…Oral microbiota are influenced by numerous factors, such as vertical transmission, diet, medical treatments and environmental and behavioural context [ 25 ]. However, these factors have only recently been investigated in Indigenous Australians, and only in the context of childhood caries [ 26 , 27 ]. Furthermore, the impact of the broader evolutionary history of microbiota has not yet been explored in Indigenous Australians.…”