Background and Aims Dysbiosis of the gut microbiota is a well-known correlate of the pathogenesis of inflammatory bowel disease [IBD]. However, few studies have examined the microbiome in very early-onset [VEO] IBD, which is defined as onset of IBD before 6 years of age. Here we focus on the viral portion of the microbiome—the virome—to assess possible viral associations with disease processes, reasoning that any viruses potentially associated with IBD might grow more robustly in younger subjects, and so be more detectable. Methods Virus-like particles [VLPs] were purified from stool samples collected from patients with VEO-IBD [n = 54] and healthy controls [n = 23], and characterized by DNA and RNA sequencing and VLP particle counts. Results The total number of VLPs was not significantly different between VEO-IBD and healthy controls. For bacterial viruses, the VEO-IBD subjects were found to have a higher ratio of Caudovirales vs to Microviridae compared to healthy controls. An increase in Caudovirales was also associated with immunosuppressive therapy. For viruses infecting human cells, Anelloviridae showed higher prevalence in VEO-IBD compared to healthy controls. Within the VEO-IBD group, higher levels of Anelloviridae DNA were also positively associated with immunosuppressive treatment. To search for new viruses, short sequences enriched in VEO-IBD samples were identified, and some could be validated in an independent cohort, although none was clearly viral; this provides sequence tags to interrogate in future studies. Conclusions These data thus document perturbations to normal viral populations associated with VEO-IBD, and provide a biomarker—Anelloviridae DNA levels—potentially useful for reporting the effectiveness of immunosuppression.

Highlights d Multi-omics reveals markers of CDI in pediatric IBD patients d Identification of metabolites reveals distinctive features for IBD and CDI d Isocaproyltaurine is made by C. difficile and associates with active IBD d Identifies biomarkers potentially useful for distinguishing disease processes

Background Recent studies have shown that oral combination antibiotics may improve disease course in refractory inflammatory bowel disease (IBD). Here, we describe the use of combination oral antibiotics as salvage therapy in refractory ulcerative colitis (UC), Crohn’s colitis, and IBD-unclassified (IBD-U) at a large pediatric IBD center. Methods Clinical response, disease activity indices, adverse events, and clinical outcomes were measured up to 1 year after antibiotic treatment in this retrospective cohort study of children with medically refractory IBD colitis. Results Sixty-three patients with refractory UC, Crohn’s colitis, and IBD-U (median age [interquartile range {IQR}], 15.3 [11.2–16.5] years; median disease duration [IQR], 1.2 [0.41–4.6] years) received a combination of 3 or 4 oral antibiotics (most commonly amoxicillin, metronidazole, and either doxycycline or ciprofloxacin) for a median (IQR) of 29 (21–58) days. Thirty-four patients (54%) were deemed corticosteroid-refractory or -dependent, with the majority (62/63) having a previous or present loss of response or primary nonresponse to anti–tumor necrosis factor alpha (anti-TNFα) therapy. Use of combination antibiotics led to a significant decrease in median Pediatric Ulcerative Colitis Activity Index (PUCAI) score (IQR) from 55 (40–65) to 10 (0–40; P < 0.0001) over 3 ± 1 weeks, with 25/63 (39.7%) patients achieving clinical remission (PUCAI <10 points). The clinical benefits of oral antibiotics were independent of anti-TNFα therapy optimization. Among children entering clinical remission (n = 25), only 1 patient required surgery at 1-year follow-up, vs 10 patients in the nonresponder group. Negative predictors of response to combination antibiotics were exposure to doxycycline (odds ratio [OR], 0.25; 95% CI, 0.08–0.76) and PUCAI ≥65 at baseline (OR, 0.2; 95% CI, 0.05–0.74). Conclusions Oral combination antibiotics appears to be an effective rescue and steroid-sparing therapy to induce remission in the short term in patients failing a biologic.