Oral Microbiota Development in Early Childhood

Abstract

Early life determinants of the oral microbiota have not been thoroughly elucidated. We studied the association of birth and early childhood characteristics with oral microbiota composition using 16 S ribosomal RNA (rRNA) gene sequencing in a population-based Swedish cohort of 59 children sampled at 6, 12 and 24 months of age. Repeated-measurement regression models adjusted for potential confounders confirmed and expanded previous knowledge about the profound shift of oral microbiota composition in early life. These alterations included increased alpha diversity, decreased beta diversity and alteration of bacterial composition with changes in relative abundance of 14 of the 20 most common operational taxonomic units (OTUs). We also found that birth characteristics, breastfeeding and antibiotic use were associated with overall phyla distribution and/or with the relative abundance of specific OTUs. Further, we detected a novel link between morning salivary cortisol level, a physiological marker of neuroendocrine activity and stress, and overall phyla distribution as well as with decreased abundance of the most common OTU mapped to the Streptococcaceae family. In conclusion, a major part of the maturation of the oral microbiome occurs during the first two years of life, and this development may be influenced by early life circumstances.

Maternal Oral Health Influences Infant Salivary Microbiome

“…Although using the V6 region of the 16S rRNA gene provides somewhat less resolution to the species level than other variable regions, our observed changes in salivary microbiome diversity with age are consistent with results of a Swedish study of 90 children sampled at 3, 6, 12, and 24 mo (Dzidic, Collado, et al 2018) and a Swedish study of 59 children sampled at 6, 12, and 24 mo of age (Kennedy et al 2019). Like these studies, we found that the relative abundance of Streptococcus spp.…”

“…Teng et al (2015) used temporal patterns of the salivary microbiome to predict onset of ECC among children followed from age 4 to 6 y, but studies describing salivary microbiome dynamics from infancy to age 2 y are few. Two Swedish cohorts revealed that the oral microbiome increases in alpha diversity during early childhood and that microbiome composition is associated with breastfeeding and route of delivery (Dzidic, Abrahamsson, et al 2018; Dzidic, Collado, et al 2018; Kennedy et al 2019). To date, there are no similar studies conducted in US high-risk populations.…”

Oral Primo-Colonizing Bacteria Modulate Inflammation and Gene Expression in Bronchial Epithelial Cells

“…Staphylococcus was the only genus detected on the first day of life, while, apart from being the most isolated genus, the Streptococcus strains were isolated in every sample from day two onward ( Figure 1 b), suggesting a persistent colonization of the oral cavity by this genus rather than a transitory passage. Our findings are in accordance with previous studies that have shown that Streptococcus is the dominant genus in the oral cavity of newborns [ 41 , 42 , 43 , 44 ]. Our intention to target the primo-colonizing bacteria was motivated by recent reports describing the early life as a pivotal time for determining the susceptibility to develop chronic respiratory diseases such as asthma.…”

Relationship Between Mutans Streptococci and Lactobacilli in the Oral Cavity and Intestine of Obese and Eutrophic Children With Early Childhood Caries—Preliminary Findings of a Cross-Sectional Study

“…In addition, they revealed a dramatic shift in the oral microbiome composition from 6 to 24 months, coinciding with the introduction of solid foods and with the period of primary tooth eruption, which provide new micro-environments for colonization. Moreover, the similarity with the maternal microbiota increases over time, leading to a more adult-like composition at 24 months (43). Differences in operational taxonomic units of bacterial genera belonging to the Firmicutes phylum were already described between a group of children fed with breast milk and a group fed with formula, combined or not with breast milk (44).…”

“…Subsequently, with the introduction of breast milk/formula (oral feedings), the gut bacteria have additional stimulus, and later, with weaning to solid foods, a more adult-like microbiota starts to develop, being further dominated by Firmicutes and Bacteroidetes (38,42). The recent investigation by Kennedy et al (43) involving a cohort of 59 children sampled at 6, 12, and 24 months highlighted that birth characteristics, breastfeeding, antibiotic use, and salivary cortisol play a significant role in the development of the oral microbiota in early childhood. In addition, they revealed a dramatic shift in the oral microbiome composition from 6 to 24 months, coinciding with the introduction of solid foods and with the period of primary tooth eruption, which provide new micro-environments for colonization.…”