Gut virome profile in new onset treatment naïve Saudi children with ulcerative colitis.

Background: Gut microbiome imbalance is well established in ulcerative colitis (UC) in Western populations. Significantly less is known about the gut virome and whether geography impacts the UC-associated microbiome. The aim of this study was to characterize gut bacteriophage changes, as well as to identify phage-bacterial associations that can serve as potential biomarkers of UC.

Methods: Twenty children with UC and 20 healthy controls were enrolled in the study. Inclusion criteria included newly diagnosed treatment-naïve children with UC with no antibiotic exposure for at least six months prior to sample collection. Deoxyribonucleic acid (DNA) was extracted from stool and rectal biopsies and was processed for shotgun metagenomic sequencing. Bioinformatics and statistical analyses were performed to assess phage diversity and their associations with gut bacteria. Candidate biomarkers were identified using the random forest classifier.

Results: In fecal samples, bacteriophage diversity was not significantly altered, but 72 species were significantly altered in UC, five of which (Salmonella_phage_SEN4, uncultured_crAssphage, Staphylococcus_phage_SPbeta-like, Streptococcus_phage_YMC-2011 and Siphoviridae_u_s) were identified as candidate biomarker signatures.

Conclusions: We found a significantly altered bacteriophage signature in children with new onset, treatment naïve UC in Saudi children, a Middle Eastern population. These changes differed from previously reported Western UC cases, indicating that demographic bias needs to be considered when developing microbiota-based diagnostics and therapeutic applications for non-Western populations.