Tongue coating microbiome characterization of Chinese preschool children with halitosis

Abstract Background: Halitosis may affect individuals of any age. However, epidemiological surveys and etiological research into halitosis among children are limited. To assess the bacterial characteristics and environmental factors associated with intra-oral halitosisamong Chinese preschool children. Methods: An epidemiological study was conducted among 273 preschool children (aged 3 to 4 years) in Shanghai, China,followed by collection of 16 samples from the tongue coating of caries-free healthy and halitosis participants according to their organoleptic score.The characterization of associated microbial communities was performed using 16S rRNA genesequencingon the MiSeq. Results: Halitosis was observed in 13.1% of the preschool children.Logistic regression analysis showed that less frequent intake of sweet snacks and mothers’ poor oral condition were associated with children’s halitosis positively. Further analysis detected the presence of 15 phyla, 24 classes, 35 orders, 53 families, 93 genera, and 226 operational taxonomic units (OTUs) in the microbial communities. In terms of microbial diversity, the tongue coating of control and halitosis groups showed no significant difference (P>0.05). Both groups shared a mass of common OTUs. The dominant bacterial genera observed in both groups included Prevotella_7(15.17% vs. 10.72%), Veillonella (13.52% vs. 10.86%), Streptococcus (13.95% vs. 18.68%),Neisseria (9.44% vs. 21.14%), Actinomyces(7.37% vs. 5.88%), Haemophilus (6.69% vs. 5.69%), andLeptotrichia (5.05% vs. 1.95%). At the genus level, the proportion of Gemellawas statistically larger in the control group (P=0.018). Conclusions: Overall, halitosis is associated with multi-microbial mutual interactions. The oral flora microorganisms may exert potentiating or inhibiting effects on each other.