Reduced incidence of Prevotella and other fermenters in intestinal microflora of autistic children Original paper

What was studied?

This study investigated autism gut microbiome Prevotella reduction by examining whether children with autism spectrum disorder (ASD) exhibit distinct intestinal microbial patterns compared with neurotypical peers. Using 16S rRNA gene pyrosequencing of fecal samples, the researchers explored how overall richness, phylogenetic diversity, and the abundance of specific genera differ in relation to autistic symptoms and gastrointestinal (GI) complaints. The work focused heavily on fermentative taxa—especially Prevotella, Coprococcus, and unclassified Veillonellaceae—to determine whether ASD is linked to a measurable loss of key carbohydrate-degrading bacteria and broader changes in microbial community structure. The study also evaluated whether dietary factors, demographics, GI severity, or autism severity explained these microbial differences, incorporating multivariate statistical models, canonical correlation analysis, and species-level interrogation of Prevotella, including OTU clustering and phylogenetic analyses.

Who was studied?

The study enrolled 40 children between the ages of 3 and 16, comprising 20 neurotypical participants and 20 children diagnosed with ASD according to ADI-R, ADOS, ATEC, and PDD-BI assessments. All ASD participants exhibited some degree of GI disturbance, while neurotypical controls were GI-symptom–free. None of the children had used antibiotics or antifungals within the previous month, minimizing confounding from acute microbiome disruption. Participants also completed diet and supplement surveys, assessing gluten-free/casein-free diets, probiotic use, seafood intake, and nutrient supplementation. Fecal samples were parent-collected, frozen, and shipped for DNA extraction and sequencing. The two groups were balanced for age and gender, although autistic children were slightly younger on average. This design allowed the researchers to separate autism-related microbial patterns from environmental or demographic factors.

Most important findings

The most striking finding was a marked loss of diversity and richness in the ASD gut microbiome. Rarefaction curves, Chao1 estimates, and phylogenetic diversity indices all demonstrated reduced microbial richness among autistic children. Importantly, these differences were linked to autistic status rather than GI severity or diet.

At the genus level, three taxa consistently distinguished the groups:

Prevotella findings were further confirmed by qPCR, reinforcing the robustness of this signal. Species-level analysis revealed that a cluster of 16 Prevotella copri–like OTUs appeared almost exclusively in neurotypical children, suggesting that loss of this phylotype is a defining community alteration. PCA and enterotype analyses showed that ASD samples lacked the Prevotella-rich enterotype entirely. Co-occurrence networks indicated that removal of Prevotella and related fermenters disrupted broader microbial community architecture.

Key implications

These findings suggest that autism is associated with a distinct intestinal ecological state characterized by diminished microbial diversity and a marked loss of fermentative, carbohydrate-degrading taxa, particularly Prevotella copri–like organisms. This altered ecosystem may influence gut physiology, immune signaling, and neuroactive metabolite production. Because these differences were not explained by diet or GI severity, the results support a model in which autism itself—or its underlying biological drivers—correlates with specific microbial signatures. Such patterns could eventually inform microbiome-based diagnostics or therapeutics targeted at restoring fermentative balance and community stability.

Citation

Kang DW, Park JG, Ilhan ZE, Wallstrom G, LaBaer J, Adams JB, Krajmalnik-Brown R. Reduced incidence of Prevotella and other fermenters in intestinal microflora of autistic children. PLoS One. 2013;8(7):e68322