Gut microbiota and irritable bowel syndrome

Irritable bowel syndrome (IBS) is the commonest functional gastrointestinal disorder, affecting between 10% and 20% of the adult population worldwide. Recently, IBS research has focused on organic components of causative factors such as gut microbiota that in turn may trigger at mucosal level low-grade inflammation and immune activation. To date, four main lines of reasoning support the role of gut microbiota in the pathogenesis of IBS: 1) IBS develops in up to 30% of individuals recovering from acute gastroenteritis "post-infective IBS"; 2) small intestinal bacterial overgrowth (SIBO) is characterized by symptoms like IBS; 3) quantitative and qualitative alterations in gut microbiota "dysbiosis "have been reported in subjects with IBS; 4) IBS symptoms can be improved by treatments (antibiotics, probiotics, prebiotics) that target the microbiota. These arguments open the way to new therapeutic options to treat patients with IBS by the administration of antibiotics, probiotics and perhaps prebiotics. Antibiotic treatment results in significant improvement rates in IBS symptoms; however, side or systemic effects, drug resistance and cost limit the chronic use. Many studies report a positive effect of probiotics, however, at present randomized placebo-controlled trials taking into account well-defined and measurable endpoints and a long follow-up should be planned.