The fecal microbiota can be used to diagnose and monitor
Crohn’s disease is a chronic inflammatory disease of the gastrointestinal tract, with most of the inflammations occurring in the small intestine, colon and/or rectum. The exact cause of Crohn’s disease is not known, but research has shown there is a clear link with changes in the composition of the gut microbiota, also called dysbiosis. Researchers have now shown that this dysbiotic state can be used to monitor and predict the disease acitivity in patients with Crohn's.
Patients with Crohn’s disease go through phases of inactive disease (remission) interspersed with periods of active inflammation (flare-ups). During inflammation, symptoms vary, depending on the part of the gut affected and the severity of the condition. The most common symptoms are diarrhoea, abdominal pain and feeling generally unwell.
The diagnosis is made based on a number of tests, including invasive methods such as endoscopy and biopsy. In order to reduce the number of inflammations and prevent complications, monitoring disease activity is important.
The exact cause of Crohn’s disease is not known, but research has shown there is a clear link with changes in the composition of the gut microbiota (dysbiosis). In addition, the level of disease activity is also associated with dysbiosis.
Researchers at Maastricht University in the Netherlands have examined ways to use dysbiosis as the basis for a non-invasive method of monitoring disease activity (1). The researchers established the disease activity in 71 Crohn patients using a combination of biochemical and clinical parameters. Faecal samples were collected at each visit to the outpatient clinic and during periods of active inflammation.
This resulted in 97 samples during flare-ups and 97 samples during remission. Subsequently, the faecal microbiota profiles were determined, followed by computer analyses to determine the differences in bacterial species between flare-up samples and remission samples. This difference was shown to concern 50 bacterial species. The next step was to determine whether this combination of bacterial species could also predict remission or active inflammation in a new group of patients. This research demonstrated that the bacterial combination could correctly predict remission in 73 percent of cases and active inflammation in 79 percent of cases (sensitivity 0.79, specificity 0.73).
Other research has also shown that the faecal microbiota may be effective in specific, non‑invasive diagnostic testing for Crohn’s disease (2). Here, faecal samples were used to determine the profiles of patients’ gut microbiota. These researchers compared the faecal microbiota of patients with that of healthy individuals. This revealed that eight microbial groups, including Faecalibacterium and Collinsella, could be used as tools in tests for diagnosing Crohn’s disease. The test was then validated in other Crohn patients, with the data showing a test sensitivity of 80 percent. This means that the correct diagnosis is made in 80 percent of cases. Subsequently, the specificity of the test (the percentage of cases in which the test correctly came back negative for Crohn’s disease) was determined using the faecal gut microbiota profiles of healthy individuals, patients with anorexia, and patients with ulcerative colitis. This showed the test to have a specificity of 94.3, 94.4 and 90.9 percent, respectively.
These research projects have demonstrated the potential of faecal microbiota profiles as a tool in diagnosing and monitoring Crohn’s disease. More research can further develop and validate this simple and non-invasive test.
The intestinal microbiota is an essential factor in driving the Crohn's inflammatory process
Read the scientific article
- Tedjo, D. I., Smolinska, A., Savelkoul, P. H., Masclee, A. A., van Schooten, F. J., Pierik, M. J., and Jonkers, D. M. (2016). The fecal microbiota as a biomarker for disease activity in Crohn’s disease. Scientific Reports, 6, 35216
- Pascal, V., Pozuelo, M., Borruel, N., Casellas, F., Campos, D., Santiago, A., & Vermeire, S. (2017). A microbial signature for Crohn's disease. Gut, 66 (5), pp. 813–822
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