Dysbiosis — an abnormal gut microbiota — is associated with several diseases, including irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD). Yet because of the great variation in gut microbiota composition between individuals, dysbiosis can be difficult to define.
In a recent article published in Alimentary Pharmacology and Therapeutics, researchers introduce a new diagnostic test that they say can help identify patients with dysbiosis. The “GA-map Dysbiosis Test” uses 16S rRNA gene sequencing to profile intestinal microbiota and identify dysbiosis.
To develop this test, they took fecal samples from healthy, IBS, and IBD patients and used PCA (principal component analysis) to build a profile of ‘normobiosis’. They used the data to develop a Dysbiosis Index (DI) algorithm; the DI is a numeric representation of the degree of dysbiosis (i.e. deviation from normobiosis). They determined that a DI greater than 2 qualifies as potentially clinically-relevant dysbiosis.
Next, researchers externally validated the test with an independent set of healthy, IBS and IBD subjects. Dysbiosis was detected in 73% of IBS patients, 70% of treatment-naive IBD patients and 80% in remission, but only in 16% of ‘healthy’ individuals.
Researchers say the test does not diagnose a particular disease, but it may allow monitoring of treatment regimens – perhaps by serving as a surrogate marker of treatment effects. Another potential clinical application is in the screening of FMT (fecal microbiota transplantation) donors.
Very little is known so far about how to address states of dysbiosis to improve health.
Casén C, et al. (2015) Deviations in human gut microbiota: a novel diagnostic test for determining dysbiosis in patients with IBS or IBD. Alimentary Pharmacology and Therapeutics DOI: 10.1111/apt.13236