Abstract Background Pediatric inflammatory bowel disease (IBD), comprising Crohn’s disease and ulcerative colitis, is increasingly recognized as a microbiome-associated condition in which perturbations of the intestinal microbial ecosystem contribute to disease initiation, immune dysregulation, and clinical exacerbations (1). Although global incidence rates of pediatric IBD continue to rise (2), high-resolution microbiome data obtained directly from intestinal mucosal biopsies remain scarce, particularly in understudied Eastern European populations. Methods This pilot study, conducted at a pediatric tertiary care center in Romania, sought to characterize mucosa-associated microbial alterations in children with confirmed IBD compared with age-matched non-IBD controls. Biopsy samples were collected during routine diagnostic endoscopy from the sigmoid and rectal mucosa, anatomical sites consistently enriched in microbial biomass. Microbiome profiling was performed using targeted 16S rRNA quantitative PCR assays to quantify selected microbial taxa and evaluate dysbiosis signatures. Results Children with IBD exhibited pronounced depletion of key beneficial commensals, including Faecalibacterium prausnitzii, Akkermansia muciniphila, and Bifidobacterium spp (p 0.05). The reduction of these health-associated genera—important for epithelial barrier maintenance, mucin turnover, and immunomodulation—highlights key functional deficits in the IBD mucosal microbiota. Conversely, IBD samples demonstrated enrichment of pro-inflammatory taxa, notably Bacteroides spp and other Enterobacteriaceae compared to the control (p 0.05). The magnitude of microbial imbalance correlated strongly with endoscopic severity indices and systemic and fecal inflammatory biomarkers, including C-reactive protein, erythrocyte sedimentation rate, and fecal calprotectin. Conclusion These preliminary findings highlight the value of biopsy-derived microbiome assessment in pediatric IBD and delineate disease-associated microbial patterns at the mucosal interface. The study provides foundational evidence supporting the development of microbiome-based diagnostic biomarkers and individualized therapeutic strategies tailored to mucosal microbial dysbiosis in pediatric IBD. References: 1. Glassner KL, Abraham BP, Quigley EMM. The microbiome and inflammatory bowel disease. J Allergy Clin Immunol. 2020;145(1):16-27. doi:10.1016/j.jaci.2019.11.003 2. Tartamus GV, Serban DE, Fogas CR, Tantau MV. Pediatric Inflammatory Bowel Disease in Romania: The First Epidemiological Study of the North-West Region (2000–2020). Children. 2025; 12(4):403. https://doi.org/10.3390/children12040403 Conflict of interest: Dr. Ionescu, Mara Ioana: No conflict of interest Mirea, Luca Mihai Daniel: No conflict of interest Ilie, Alexandra: No conflict of interest Radulescu, Raluca: No conflict of interest Galos, Felicia: No conflict of interest Gradisteanu Pircalabioru, Gratiela: No conflict of interest
Ionescu et al. (Thu,) studied this question.