Microbiome variations in preschool children with halitosis

Objective To assess the bacterial characteristics associated with intra-oral halitosis among Chinese preschool children. Methods An epidemiological study was conducted among 273 preschool children (aged 3-4 years) in Shanghai, China, followed by the collection of 16 samples from the tongue coating of caries-free healthy and halitosis participants. The characterization of associated microbial communities was performed using 16S rRNA gene sequencing on the MiSeq. Results Halitosis was observed in 13.2% of the preschool children. No significant difference in terms of microbial diversity (p > .05) was detected in the control and halitosis groups. The dominant bacterial genera observed in both groups included Prevotella, Veillonella, Streptococcus, Neisseria, Actinomyces, Haemophilus, and Leptotrichia. The relative proportions of thirteen species (including Leptotrichia sp. HMT_417, Prevotella Pallens, and Alloprevotella rava) were significantly higher in the halitosis group compared with the control group, whereas the distribution of seventeen species from genera Streptococcus, Gemella, and Kingella showed a higher abundance in the control group. Further investigation of interactions among species demonstrated obvious differences in two groups, indicating that various microorganisms interact to produce halitosis in preschool children. Conclusions Overall, halitosis is associated with multi-microbial mutual interactions. The oral flora microorganisms may exert potentiating or inhibiting effects on each other.