A role for the gut microbiota in IBS

Key PointsAnimal studies have demonstrated that changes in the gut microbiota result in altered host function, in domains relevant to IBS (gut motility, visceral pain responses, intestinal permeability, and brain function and behaviour)Gut microbiota composition is altered in at least a subset of patients with IBS (most commonly diarrhoea-predominant IBS), but no microbial 'signature' that could act as an IBS biomarker has been identifiedConsiderable interest exists in the ability of bacteria to produce substances that interact with the host to influence gut and brain function, which include fatty acids, tryptophan and neurotransmittersDysbiosis in IBS is characterized by a loss of microbial diversity and temporal instability; contributing factors include diet, stress, infection, antibiotic usage, immune activation and low-grade inflammationThe gut microbiota from patients with IBS, but not healthy individuals, can induce gut dysfunction in mice reminiscent of that seen in IBS, strongly suggesting that the microbiota contributes to the expression of IBSEmerging evidence supports the efficacy of select and limited microbiota-directed therapies in treating IBS, and to date these include prebiotics, probiotics and selected antibiotics