Maternal Oral Health Influences Infant Salivary Microbiome

Abstract

Oral microbiomes vary in cariogenic potential; these differences may be established early in life. A major concern is whether mothers transmit cariogenic bacteria to their children. Here we characterize early salivary microbiome development and the potential associations of that development with route of delivery, breastfeeding, and mother's oral health, and we evaluate transmission of microbes between mother and child. We analyzed saliva and metadata from the Center for Oral Health Research in Appalachia. For this cohort study, we sequenced the V6 region of the 16S rRNA gene and used quantitative polymerase chain reaction to detect Streptococcus mitis, Streptococcus sobrinus, Streptococcus mutans, Streptococcus oralis, and Candida albicans in the saliva from mothers and their infants, collected at 2, 9, and 12 mo (Pennsylvania site) and 2, 12, and 24 mo (West Virginia site). Breastfed children had lower relative abundances of Prevotella and Veillonella. If mothers had decayed, missing, or filled teeth, children had greater abundances of Veillonella and Actinomyces. There was little evidence of maternal transmission of selected microbes. At 12 mo, children's microbiomes were more similar to other children's than to their mothers'. Infants' salivary microbiomes became more adult-like with age but still differed with mothers' microbiomes at 12 mo. There was little evidence supporting transmission of selected microbes from mothers to children, but risk of colonization was associated with tooth emergence. Children are likely to acquire cariogenic bacteria from a variety of sources, including foods and contact with other children and adults.

Keywords: 16S rRNA; caries; early childhood caries; epidemiology; gingivitis; oral microbiome.

Figure 1.

Flowchart of study participants and selected samples during the postpartum period. Mothers and infants participating in the COHRA 2 (Center for Oral Health Research in Appalachia) from Pennsylvania (n = 154) and West Virginia (n = 48).

Figure 2.

Characteristics of observed community state types (CSTs) and transition probabilities of changing among CSTs during follow-up. (A) Waffle plots of the 3 CSTs observed among infants; observed mean alpha diversity (Shannon index) is noted. (B) Changes in salivary CSTs by route of delivery with infant age: vaginal (n = 69), cesarean section (n = 30), unknown (n = 2). (C) Dynamics of salivary CSTs among 2-, 6-, and 12-mo visits of Pennsylvania infants (n = 77). (D) Dynamics of CSTs among 2-, 12-, and 24-mo visits of West Virginia infants (n = 24, n = 22 at 24 mo). Infants participating in the COHRA 2 (Center for Oral Health Research in Appalachia) from Pennsylvania and West Virginia.

Figure 3.

Models of log-transformed relative abundance of the top 10 genera (continuous) adjusted for collection site (Pennsylvania vs. West Virginia), repeated measures over time, and selected variables. (A) Infant age (months). Note that the confidence limits for Streptococcus are too small to be visualized on the figure (odds ratio, 0.94; 95% CI, 0.93 to 0.95). (B) Route of delivery (categorical) adjusted for infant age. (C) Breastfeeding status (binary) adjusted for infant age and route of delivery. (D) Mother’s oral health status (categorical) at baseline adjusted for infant age. Infants participating in the COHRA 2 (Center for Oral Health Research in Appalachia) from Pennsylvania and West Virginia (303 observations from 101 individuals). *Panel A x-axis scale differs from panels B, C, and D.

Figure 4.

Probability of transmission from mother to infant of selected species by infant age (months), given that mother tested positive at any time point: (A) Pennsylvania (n = 77) and (B) West Virginia (n = 24). Values were imputed for 122 of 505 samples. Mothers and infants participating in the COHRA 2 (Center for Oral Health Research in Appalachia) from Pennsylvania and West Virginia. Error bars indicate 95% CIs.