A novel tool for noninvasive diagnosis and tracking of patients with inflammatory bowel disease

BACKGROUND: The pathogenesis of inflammatory bowel disease (IBD) involves the role of bacteria. These bacteria ferment nonstarch polysaccharides in the colon producing a fermentation profile that through altered gut permeability can be traced in urine. We proposed to track the resultant volatile organic compounds or gases that emanate from urine using noninvasive real-time tools, specifically by electronic nose and Field Asymmetric Ion Mobility Spectrometer (FAIMS) instruments. The aim of this study was to determine the utility of electronic nose and FAIMS instruments to detect and track the fermentation profile of patients with IBD.

METHODS: Sixty-two individuals were recruited, 48 individuals with IBD (24 with Crohn's disease and ulcerative colitis, respectively) and 14 controls. The disease activity was recorded, and urine samples were collected. The headspace (the air above the sample) was analyzed using the electronic nose and FAIMS instruments.

RESULTS: Electronic nose data analysis was conducted through (1) Principal Component Analysis (data were analyzed together without previous categorization); and (2) Discriminant Function Analysis (samples were precategorized [clinical groups]). The FAIMS data were processed by Fisher's Discriminant Analysis (precategorized [clinical groups]). Both technologies consistently showed the ability to separate those with IBD and controls with a >75% accuracy; P < 0.001. In a smaller subgroup (n = 24), we also demonstrated that the electronic nose and FAIMS instruments can distinguish between active disease and those in remission.

CONCLUSIONS: The fermentation profile or fermentome is disparate in those with IBD compared with controls--a reflection of the bacterial diversity in health and disease. This profile also changes (and was tracked) as the disease is induced into remission. Thus, the electronic nose and FAIMS instruments offer the potential of a noninvasive real-time diagnostic tool for point of care clinical use.