Assessment of the relationship between oral microbiota and autism spectrum disorders in children with primary dentition

Autism Spectrum Disorder (ASD) is associated with several abnormalities in the oropharyngeal region together with dysbiosis in oral microbiota. As the beginning of the gastrointestinal system, the oral cavity is accepted as a part of the link mediated by the microbiota gut brain axis in ASD. There are studies reporting alterations in oral microbiota of children with ASD. The aim of this study was to investigate possible alterations of the saliva microbiota in children with ASD compare with healthy controls. The saliva microbiota of children with ASD (n = 9) and healthy controls (n = 9) between 36-60 months (mean 47.78 ± 8.54 months) were analyzed using 16S rRNA gene sequencing analysis method and investigated the differences related to ASD. In results, while the relative abundance amount of Flavobacteriales order in the group with ASD was higher than the controls, the relative abundance amount of the Fusobacteriales order in the group with ASD was found to be lower than the control group. In the group with ASD, Granulicatella elegans, Streptococcus anginosus SK52 = DSM 2563, Streptococcus cristatus AS 1.389, Streptococcus mitis, Streptococcus oralis subsp. dentisani, Streptococcus pneumoniae and Neisseria zalophi taxa were observed at higher rates with significant differences. There was no significant difference between the groups in terms of alpha diversity indices. In addition, positive correlation was found between Firmicutes phylum, Bacilli class and Lactobacillales order and body mass index in the group with ASD. The data obtained from the study show the increasing and decreasing tendencies of some taxa at different levels when the oral microbiota of children with ASD is compared with healthy controls. With understanding the relationship between ASD and oral microbiota, it is thought that oral microbiota can be used as a potential tool in the investigation of phenotypes associated with ASD. Key Words: oral microbiota, autism spectrum disorder, brain-gut axis, 16S rRNA analysis