Researchers Find Cavity-causing Bacteria in Infants

Researchers at the University of Illinois have confirmed the presence of bacteria associated with early childhood caries (ECC) in infant saliva. The research, which was published in PLoS One in the article “Comparative analysis of salivary bacterial microbiome diversity in edentulous infants and their mothers or primary care givers using pyrosequencing,” confirms the need for infant oral care.

ECC is a virulent form of caries, more commonly known as tooth decay or a cavity. Cavities are the most prevalent infectious disease in US children, according to the Centers for Disease Control and Prevention. The researchers noted that by kindergarten, 40% of children have dental cavities. Kelly Swanson, lead researcher in the product also commented, “In addition, populations who are of low socioeconomic status, who consume a diet high in sugar and whose mothers have low education levels are 32 times more likely to have this disease.”

The researchers used pyrosequencing to phylogenetically characterize the salivary bacterial microbiome of edentulous infants and to make comparisons against their mothers. Saliva samples were collected from five edentulous infants (mean age = 4.6±1.2 mo old) and their mothers or primary care givers (mean age = 30.8±9.5 y old). Salivary DNA was extracted, used to generate DNA amplicons of the V4–V6 hypervariable region of the bacterial 16S rDNA gene, and subjected to 454-pyrosequencing. On average, over 80,000 sequences per sample were generated. High bacterial diversity was noted in the saliva of adults [1012 operational taxonomical units (OTU) at 3% divergence] and infants (578 OTU at 3% divergence). Firmicutes, proteobacteria, actinobacteria, and fusobacteria were predominant bacterial phyla present in all samples. A total of 397 bacterial genera were present in the dataset. Of the 28 genera different (P<0.05) between infants and adults, 27 had a greater prevalence in adults. The exception was Streptococcus, which was the predominant genera in infant saliva (62.2% in infants vs. 20.4% in adults; P<0.05). However, Veillonella and Neisseria are also predominant bacterial genera present in infants.

The researchers, therefore demonstrated that although the adult saliva bacterial microbiome had a greater OTU count than infants, a rich bacterial community exists in the infant oral cavity prior to tooth eruption. These species lead to biofilm formation and are associated with ECC. The researchers noted that their findings necessitate more research on the evolution of the infant oral bacterial community. The researchers want to characterize the microbial evolution that occurs in the oral cavity between birth and tooth eruption, as teeth erupt and as dietary changes occur such as breastfeeding vs. formula feeding, liquid to solid food and changes in nutrient profile. They believe that the soft tissues in the mouth serve as reservoirs for potential pathogens prior to tooth eruption, and they hypothesize that manipulating the bacterial community in infants before tooth eruption could help prevent this disease. The study noted that while the previous “window of infectivity,” was thought to occur between 19 and 33 months, it occurs much younger.

To prevent dental cavities from occurring in baby teeth, the American Academy of Pediatric Dentistry recommends minimizing snacks and drinks with fermentable sugars and wiping the gums of babies without teeth. The researchers note that educating parents on oral hygiene and dietary habits is the most important strategy for prevention of dental cavities. It may also lead to the development of more gentle oral care products for infants.

Additional researchers included: Kimberly Cephas, Juhee Kim, Rose Ann Mathai and Kathleen Barry of the University of Illinois at Urbana-Champaign; Scot Dowd of the Research and Testing Laboratory and Medical Biofilm Research Institute; and Brandon Meline of the Champaign-Urbana Public Health District. This study was funded by the United States Department of Agriculture-Cooperative State Research, Education and Extension Service (project ILLU-538-396).

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