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P691. New test for profiling of the gut microbiota in non-IBD and IBD patients

H. Vebø1, C. Casen1, D. Vangen1, F.T. Hegge1, G. Perminov2, P. Ricanec3, M.H. Vatn4, 1Genetic Analysis AS, Oslo, Norway, 2Oslo University Hospital, Department of pediatrics, Oslo, Norway, 3Oslo University Hospital, Department of Gastroenterology, Oslo, Norway, 4Oslo University Hospital, Department of Medicine, Oslo, Norway

Background

As the awareness of the effect of the gut microbiota on health is increasing, there is a need to find tools to study changes in the gut microbiota. The GA-mapTM technology platform has been developed to demonstrate profiles of the composition of gut microbiota. The platform provides analysis of a large number of faecal samples in a cost-effective way. A sub-cohort from the IBSEN II study cohort has been analysed together with a population of normal subjects on the GA non-IBD/IBD test.

Methods

Based on peer-reviewed literature and a test optimizing development work, special sets of DNA probes are designed that facilitate bacterial profile separation between the patient groups IBD and non-IBD, and normal subjects. The assay was tested against 187 samples from the IBSEN II cohort, comprising treatment naïve IBD patients and symptomatic non-IBD patients. The samples were collected before colonoscopy. In addition a population of 84 normal subjects with no clinical signs of gut disorder (not confirmed by colonoscopy) was included. The GA non-IBD/IBD test was performed essentially as described in [1], using Luminex MagPix system for detection and quantification of labelled DNA probes (indicative of presence of different bacteria). The signals from each DNA probe in each sample were subject to PCA analysis and a model was developed based on leave-one-out cross-validation.

Results

The results from non-IBD versus IBD patients in the IBSEN II study cohort, gave 78% sensitivity and 70% specificity (n = 187), with a PPV of 76.6% and a NPV of 71.3%. Looking at IBD patients versus normal subjects a sensitivity of 89% and specificity of 88% was observed (n = 182), with PPV and NPV of 96% and 82%, respectively. Finally, non-IBD patients versus normal subjects showed 74% sensitivity and 82% specificity (n = 167), and PPV 79% and NPV 79%. Age-group of subjects ranged from 18 to 55 years.

Conclusion

The GA non-IBD/IBD test gives a unique opportunity to study specific profiles of the gut microbiota that may be associated with non-IBD and/or IBD related diseases compared to gut microbiota profiles in normal subjects. The present results suggest that the GA test may be a useful tool in differentiating between IBD, non-IBD and normal subjects, and thus an aid in the diagnosis and follow up of patients.

1. Vebø H et al., (2011), Temporal Development of the Infant Gut Microbiota in Immunoglobulin E-Sensitized and Nonsensitized Children Determined by the GA-Map Infant Array, American Society for Microbiology, Clinical and Vaccine Immunology, 18(8): 1326–35.