Michael G Burke, MD
A comparative analysis of the feces of infants with and without colic indicated that intestinal inflammation is associated with colic. Further, compared with noncolicky babies, those with colic were shown to have in their gut microbiota a greater abundance of some less favorable organisms and fewer of others known to be beneficial.
Participants were 65 infants (aged 21 to 90 days): 37 had colic (crying and fussing more than 3 hours a day) and 28 were noncolicky (control group). Crying and fussing time was about 5 hours a day in the group with colic and less than 1 hour in the control group.
To test for intestinal inflammation, investigators analyzed fecal calprotectin levels, finding that calprotectin was elevated in babies with colic regardless of whether they were fed breast milk or formula. In fact, analysis that adjusted for variables such as feeding type and crying plus fussing time and age showed that colic is the only independent predictor of fecal calprotectin levels, which were an average of 95 µg/g higher in colicky infants than in their noncolicky counterparts.
Overall, fecal analysis showed microbial diversity was greatest in exclusively formula-fed babies and lowest in breastfed controls, with the microbiota of babies with colic containing many more species than the microbiota of controls. Although investigators did not find that any major differences in species diversity were attributable to colic, they did determine that the stools of colicky babies, compared with noncolicky infants, were characterized by a significant decrease in the relative abundance of Actinobacteria and a marginal increase in Proteobacteria, a proinflammatory microorganism.
The researchers also found that more than 95% of the reduction of organisms of the Actinobacteria phylum was attributable to the species Bifidobacterium, an anti-inflammatory organism. Indeed, in infants with colic, Bifidobacterium represented only 0.3% of total bacteria compared with 10% in noncolicky infants. Acinetobacter and Lactobacillus iners were species significantly associated with colic (Rhoads JM, et al. J Pediatr. August 31, 2018 [epub ahead of print]).
Thoughts from Dr. Burke
It may be that, after hundreds of years of caring for colicky babies and more than 60 years of investigation focusing on the gastrointestinal (GI) tract as the possible source of babies’ distress, pediatric researchers are bringing into focus the cause of infantile colic. This study provides a potential mechanism for previous observations that probiotics may moderate colic, and it reinforces our expanding understanding of the importance of the human microbiome.