A Study on Bacteria in Saliva of Autistic Children at Early Life

Background: Studies have shown that oral bacteria are involved in the occurrence of some neurological diseases. Autism spectrum disorder (ASD), a neurodevelopmental disorder occurring in early life, is closely related to intestinal bacteria. At present, the role of the oral microbiota in ASD rarely remains unexplored. Objectives: This study aimed to explore the differences of bacteria in saliva between autistic and healthy children in early childhood and investigate whether there are any specific salivary bacteria serving as biomarkers of ASD. Methods: A total of 10 autistic children aged 2 - 6 years and 10 healthy children matched in age, gender, and region in China were involved in this study. 16S ribosomal ribonucleic acid sequencing was employed to detect the disparities of bacteria in saliva between autistic children and healthy children. Moreover, the relationship between salivary differential bacteria and intestinal bacteria in autistic children was analyzed to screen out salivary differential bacteria that were unrelated to intestinal bacteria. Results: There were 14 bacteria in the saliva of children with autism, which were different from those of the control group (P < 0.05). Correlation analysis showed that the salivary Bacteroides fragilis had no apparent relationship with intestinal bacteria (P > 0.05); nevertheless, the rest of the differential bacteria in saliva were significantly related to intestinal bacteria. Conclusions: There were differential bacteria in the saliva of children with ASD and healthy controls, indicating that salivary bacteria might play a role in ASD. Nevertheless, further studies are needed to identify the pathogenesis of ASD.