A pilot case-control study on the microbiota of pediatric FAP-NOS and the role of early life stress
Background  Gut microbial features and the role of early life stress in pediatric functional abdominal pain – not otherwise specified (FAP-NOS) have never been investigated before. Here we hypothesize that occurrence of early life stress is higher in FAP-NOS compared to healthy controls and that fecal microbial profiles and related metabolites differ between groups. Methods In an international multicenter case-control study FAP-NOS patients (n = 40) were compared to healthy controls (n = 55). Stool samples and demographic and clinical data including early life traumatic events and antibiotics treatments were collected from children aged four to twelve years. Fecal microbial profiles were assessed with 16S rRNA gene amplicon sequencing. Microbial metabolite concentrations in fecal supernatant, including short chain fatty acids and amino acids, were detected via liquid chromatography.  Results Microbial richness was increased in FAP-NOS compared to healthy controls and microbial composition (unweighted Unifrac) differed between groups. Three distinct amplicon sequencing variants and two distinct species were enriched in FAP-NOS compared to controls, with no observed changes at higher taxonomic levels. No differences in microbial metabolites, and early life stress were observed between groups. Conclusion The presented hypothesis could not be proven, with no observed differences in occurrence of early life stress, and fecal microbial metabolic profiles between pediatric FAP-NOS and healthy controls. Pediatric FAP-NOS patients exhibited mild differences in fecal microbial community when compared with controls. Further large-scale studies with high-resolution techniques are warranted to address the biological relevance of present observations.