Follow-up-IBS
Follow-up of faecal microbiota in IBS patients
Irritable bowel syndrome (IBS) is the most common functional                 gastrointestinal disorder in western countries. The definition and treatment of IBS                 is challenging due to its largely unknown aetiology and the variety of symptoms it                 can present. Previous studies on IBS suggest subtle alterations in the composition                 of intestinal microbiota. However, no consensus has been reached regarding the                 association between specific bacteria and IBS. To overcome the confusion introduced                 by inter-subject variability and heterogeneity within IBS that is problematic in                 cross-sectional studies, we undertook a longitudinal study that allowed us to                 compare samples from single patients at moments with different type and/or severity                 of symptoms. We present results for two IBS patients with diarrhoea subtype and the                 healthy relative of one of them. Faecal samples collected every two days the first                 week and then weekly over two months were analysed through metagenomic and                 metatranscriptomic approaches. Overall, we detect a greater instability of faecal                 microbiota in IBS patients when compared to the control, and even larger instability                 associated with acute diarrheoa. Bacterial composition and encoded functions were                 fairly stable throughout. On the contrary, the fraction of active bacteria varied                 markedly in time. Strong and quick compositional shifts were associated with                 relapse, although with low reproducibility between and within patients. Similarly,                 changes in the global pattern of gene expression characterized days of worsening,                 but we could not identify genes or functions associated with relapse. Our results                 confirm that the association of microbiota with IBS is rather weak.