The Microbiome–Gut–Brain Axis and the Consequences of Infection and Dysbiosis

It is generally well accepted that the gut microbiome can have significant effects on the structure and function of the enteric and central nervous systems including behavior. Here we review these and comment on how they may occur as a result of dietary change, antibiotics, or the administration of nutritional supplements such as probiotics or prebiotics. We use as an example of the microbiome–gut–brain axis, irritable bowel syndrome (IBS), as it is a globally prevalent disorder and comorbid with psychiatric diseases, and one of its known causes or triggers is infectious gastroenteritis. We also review possible pathways that may be involved in alteration of brain functions including nervous and humoral ones, and the importance of timing of the insult from pregnancy to adolescent or adult. Finally, we comment on growing information about the gut virome, and the realization that this may tie into our beginning of the understanding of the interactions between diet, bacterial microbiome, and brain function.