LONGITUDINAL ASSESSMENT OF MICROBIAL DIVERSITY FOLLOWING CAMPYLOBACTER INFECTION ASSOCIATES WITH PROTEOLYTIC ACTIVITY CHANGES IN POST-INFECTION IRRITABLE BOWEL SYNDROME

Background: Approximately 15% of individuals develop post-infection irritable bowel syndrome (PI-IBS) after Campylobacter infection. Our previous work shows 40% of PI-IBS patients have high fecal proteolytic activity (PA) and changes in microbiota composition. Commensal microbes suppress proteases; however, it is unclear how microbial diversity changes over time following infection and whether that associates with impaired protease states. Aim: Determine longitudinal changes in diversity and composition and microbial signatures associating with high and low PA PI-IBS development. Methods: Patients with C. jejuni infection provided stool samples and diet information every two months after acute infection. PI-IBS status and PA were assessed at 6-months by a FITC-casein cleavage assay (high PA >1078 BAEE Units/mg). Shotgun metagenomic sequencing was performed and summarized into α-diversity, β-diversity, taxa abundances, and predictive pathway analysis. Linear mixed-effects model and PERMANOVA were used to test timepoint associations. Results: Nineteen patients were enrolled and longitudinally followed with 10 developing PI-IBS defined by Rome III criteria, with 6 low PA (age 54±10, 3F) and 4 high PA (age 27±5, 2F). Similar caloric intake was observed at all timepoints except at 12 months with higher protein in high PA (22±0.1 vs 17±0.8%, T-test, p = 0.01). Longitudinally, alpha diversity was significantly lower in high PA (Shannon, p = 0.03, Figure 1), particularly at 6 months following infection (Shannon, p = 0.008). Beta diversity differed between high and low PA longitudinally (p = 0.02) and at early as well as late timepoints (2,6,12-months, p < 0.05). Increased abundances of Blautia hansenii and Coprococcus ssp. HPP0048 (FDR < 0.2) in high PA and increased abundance of several Alistipes spp. in low PA were seen (FDR < 0.2). On predictive pathway analysis, high PA PI-IBS patients demonstrated increased bacterial secretion system, carbon fixation, mineral and organic ion transport system, and methane metabolism (FDR < 0.2). However, carbohydrate metabolism pathways were decreased in high PA compared to low PA PI-IBS (FDR < 0.2). Conclusions: High PA PI-IBS patients have decreased alpha diversity and changes in beta diversity that start early and remain consistent over time after Campylobacter infection. The decreased carbohydrate metabolism in high PA is indicative of increased proteolytic fermentation which is known to be detrimental to intestinal epithelium. A pre-infection vulnerability or an inability of the microbiota to recover post-infection and the resulting loss of key commensals, consistent with our previous studies, may lead to persistently high PA with resulting outcomes of barrier loss and visceral hypersensitivity. Supported by DK 127998 and DK103911.