Sex-specific differences in the salivary microbiome of caries-active children

Abstract

Background and Objectives: Dental caries is a chronic disease affecting young children and has multi-factorial risk factors. The purpose of this work was to identify sex-specific differences in the salivary microbiota within caries-active children. Design: Saliva specimens were collected from 85 children (boys: 41; girls: 44) between the ages of 2-12 years. Salivary microbial DNA was subjected to PCR amplification using V3-V4 16S rDNA-specific primers and next-generation sequencing. Results: Significant sex differences in salivary microbiota were found between caries-active boys versus caries-active girls. Neisseria flavescens, Rothia aeria, and Haemophilus pittmaniae were found at significantly higher levels in caries-active boys. In contrast, Lactococcus lactis, Selenomonas species HOT 126, Actinobaculum species HOT 183, Veillonella parvula, and Alloprevotella species HOT 473 were found at significantly higher levels in caries-active girls. Conclusion: We have found the acid-generating, cariogenic Lactococcus lactis to be much more abundant in caries-active girls than caries-active boys, indicating that this microorganism may play a more significant role in shaping the cariogenic microbiome in girls. In addition, in caries-active girls, Alloprevotella species HOT 473 was the only species that exhibited both significant sex differences (4.4-fold difference; p=0.0003) as well as high abundance in numbers (1.85% of the total microbial population).

High abundance of sugar metabolisers in saliva of children with caries

“…Our finding on Selenomonas is discordant between sexes. Ortiz et al 25 showed that Selenomonas sps were associated with caries in girls, and a notably greater abundance of Selenomonas Genus probe 1 was observed with less frequent teeth brushing in adolescents with caries 20 , which is in line with our finding in girls. Taken together, we found that most of the caries-associated taxa were acid producers that cause demineralisation of tooth enamel.…”

“…However, our results are consistent with other studies that demonstrate that caries is more common in girls than in boys 34 , 35 . Ortiz et al 25 examined the sex-specific differences in the saliva microbiota in children with active caries and identified several species (including Rothia aeria, Neisseria flavescens , and Haemophilus pittmaniae ) that were higher in boys with active caries. Our findings are in line with these observations.…”

“…While the genus Rothia is a key member of the saliva microbiota in persons with caries, its role is largely unknown 36 , 37 . The majority of the Neisseria species are assumed to be acid producers and therefore enhance the development of a cariogenic environment 25 . We found that Haemophilus was higher in boys with caries; however, the genus Haemophilus was also reported in the saliva microbiota in those with low levels of caries 38 .…”

“…Some pilot studies have suggested that alterations in the saliva microbiota correlate with caries development in children 23 , 24 . However, neither age nor sex was considered in the analysis; we, and others, have demonstrated that the composition of saliva microbiota is sex-specific in children 2 , 25 , 26 .…”

The evolutionary history of the human oral microbiota and its implications for modern health

“…Biological differences among people can contribute to oral microbiota diversity and composition. Sex‐based differences have been reported in individuals that were stratified by disease status, 27 when large cohorts were examined, 28 in multple studies 29 . Age is also a critical factor, as oral microbiota change over time, 30,31 especially as older adults begin to wear dentures 32 .…”