Crying in infants: on the possible role of intestinal microbiota in the development of colic.

Up to around a quarter of all infants cry excessively and unsoothably during their first months of life. This phenomenon has been termed "infant colic." In most cases, physicians are unable to determine the cause of the colicky behavior. In a recent study, and by means of comprehensive and deep analyses of more than 1000 intestinal phylotypes, we found that infants with colic showed lower microbiota diversity and stability than control infants in the first weeks of life. Colic-control differences in the abundance of certain bacteria were also found at 2 weeks. These microbial signatures possibly explain the colic phenotype. In this addendum we discuss other recent publications on the subject and present previously unpublished analyses of our own. We address possible mechanisms behind the links between microbiota and crying, and present future directions that could further help elucidate the hypothesized relations between intestinal microbiota and infant colic.