P.174 DIAGNOSTIC ROLE OF CAPSULE ENDOSCOPY IN PATIENTS WITH SYMPTOMS HIGHLY COMPATIBLE WITH CROHN'S DISEASE

Abstract

Background: Resident colonic bacteria, principally anaerobes and firmicutes, ferment undigested fibre, leading to the formation of volatile organic compounds (VOC). These are passed in faeces but also possibly absorbed and excreted in the urine. We hypothesised that the “fermentation profile” (FP), as seen in faeces and urine, may differ in health and in inflammatory bowel disease (IBD), and in the latter may change as the patient responds to treatment. Aim: Pilot study to determine if FP in faeces and urine can be recognised and reliably measured and to examine if there were identifiable differences in health and IBD. Methods: Healthy volunteers n=2; Longitudinal study of IBD patients: ulcerative colitis (UC) n=1, studied when acutely ill and when better on treatment; Crohn's disease (CD) n=1, at the beginning and during the course of Infliximab therapy. Samples of faeces and urine were analysed fresh and after storage for 2 weeks. VOC were released by heating (thermal desorption, TD) separated by gas chromatography (GC) and identified by mass spectroscopy (MS). The noise in GC data was cleaned using Clearview software ©Markes. Results: Initial technical developments were made using horse, cow and chicken faeces: each showed a very large number of peaks, some shared. Volunteers within-run variability: <15% for faeces but <10% for urine, reflecting its more uniform nature. Data from urine VOC is presented here. All individuals showed a wide range of peaks, which could be grouped into 5 broad categories (expressed as % of total compounds present). IBD patients showed higher levels of TAK but lower levels of TOA. The IBD VOC profile changed with improvement on treatment: CD: HB Index fell from 4 to 0 at week 6; the TOA and PG levels fluctuated. UC: SCA Index fell from 4 to 3; VOC profile showed changes similar to those in CD and in addition, loss of high molecular weight compounds. Conclusion: We have observed: 1 Clear differences in VOC profiles between healthy volunteers and IBD patients 2 Improvement in IBD during treatment was associated with change in VOC profile. We believe the study of FPs using TD-GC/MS offers new insights into gut health which have clinical relevance.