169 Assessment of Community Structure and Predictive Functional Profiling of the Mucosa-Associated Microbiome Implicates Alterations in Benzoate Metabolism in ‘de novo’ IBD After Pouch-Surgery and in Treatment-Naïve Pediatric IBD

Abstract

of patients were identified: those developing early ER (N=12) and patients without ER (N=18) (Figure 1). Before surgery, a reduction of the Lachnospiraceae family (p=0.05) and Clostridium XVIII genus (p=0.032) was seen in the predominant microbiota of patients developing early postoperative ER whereas 3 members of Clostridium XIVa genus (p=0.073), Veillonellaceae family (p=0.028) and Bifidobacterium genus (p=0.01) were higher in patients with ER compared to patients without ER. A score combining these five bacterial risk factors was calculated and showed an area under the curve of 0.87 (95% CI, 0.76–0.99). The occurrence of two or more risk factors had a sensitivity, specificity, positive predictive value, and negative predictive value of 100%, 56%, 60% and 100% respectively. At the time of postoperative endoscopy, we observed an overrepresentation of Lactobacillus genus (p=0.003) and Ruminococcus gauvreauii (p=0.01) in the patients with ER. Conclusions: An overrepresentation of Clostridium XIVa spp., Veillonellaceae, Bifidobacteria and a lower abundance of Lachnospiraceae and Clostridium XVIII spp. in the predominant profile of preoperative fecal samples is associated with a higher risk to develop postoperative ER following ileocaecal resection. At the time of postoperative endoscopy, the predominant microbiota from patients with ER also differs from patients without recurrence, with as most prominent players lactobacilli and R. gauvreauii.