Colic Preceded by Gut Flora Differences

Yael Waknine

January 14, 2013

Early differences in the development and composition of gut flora may be at the root of infant colic, according to a study published online January 14 in Pediatrics.

Using DNA technology, Carolina de Weerth, PhD, from Radboud University in Nijmegen, the Netherlands, and colleagues followed the temporal development of intestinal microbiota from birth to approximately 100 days in 24 infants.

At 2 weeks, babies later diagnosed with colic had significantly less microbial diversity and stability than their healthy counterparts. Moreover, the infants with colic had more than twice the abundance of proteobacteria (including groups related to Escherichia coli, Enterobacter aerogenes, Pseudomonas, and Yersinia) and significantly reduced levels of Bacteroidetes, including bifidobacteria and lactobacilli.

At that point, the link between crying as an environmental variable and group differences in gut flora became significant in multivariate analysis, being positively correlated with the presence of pathogenic bacteria and negatively linked to butyrate-producing species.

"Remarkably, the differences between colic and control microbiota were all seen in the first month of life, before the colic peak takes place," the authors write, noting that the difference usually disappeared by 3 to 4 months of age, when babies' colic usually resolves.

Although disparities in gut flora have long been thought to cause colic by affecting motor function and gas production, prior studies have focused on 6-week-old infants diagnosed with the condition, and standard culture techniques have produced limited results.

According to the authors, recent advancements in molecular technology have revealed that the intestinal tract, which is virtually sterile at birth, is rapidly colonized in early life according to specific patterns of microbial succession that ultimately result in a complex ecosystem similar to that of adults.

Analyzed With Genetic Microarray

To determine whether early deviations in the colonization process might apply to the etiology of infant colic, investigators analyzed the temporal development of intestinal microbiota from birth onward in 12 infants with and 12 infants without colic. The current study is part of a larger prospective study that includes 160 healthy infants; parents in the overall study collected stool samples at prespecified times between birth and 100 days.

The investigators used cry diaries to diagnose colic at 6 weeks. Sex distribution, birth weight, place and mode of delivery, and breast-feeding duration were highly similar between the colic and no-colic groups selected from the larger study population.

Fecal extraction yielded 210 useable samples that were analyzed using the human intestinal tract chip (a genetic microarray with more than 1000 intestinal phylotypes that comprehensively addressed an array of microbiota not covered by standard culture techniques).

Although both groups exhibited temporal variability in gut flora composition, Dr. de Weerth and colleagues found significant differences within the first few weeks of life. Infants with colic were characterized by an intestinal microbial environment that developed more slowly and with decreased temporal stability.

Specifically, colicky infants exhibited significantly decreased diversity in gut flora compared with their healthy counterparts at 14 and 28 days (P < .02 and P < .01, respectively), a trend that continued during the first 100 days of life. In contrast, healthy infants showed slight increases in diversity over time. Analysis of successive fecal samples revealed that microbial stability was particularly low at 1 and 2 weeks in the colicky infants (P < .04).

Moreover, by 2 weeks of age, samples from colicky infants contained more than double the level of proteobacteria (Anaerobiospinillum spp, E aerogenes et rel, E coli et rel, Haemophilus, Klebsiella pneumonia et rel, Pseudomonas spp, Serratia spp, Vibrio spp, and Yersinia et rel) compared with their healthy counterparts (relative abundance, 25.67% ± 27.47% vs 9.99% ± 15.47%; P = .037), and counts remained highly elevated for the duration of the study.

Infants with colic also had lower Bacteroidetes counts than their healthy counterparts for the entire period, with various levels of significance in the first 2 months (14 days, 7.95% ± 17.68% vs 11.38% ± 17.09% [P = .975]; 79 days, 1.47% ± 0.40% vs 10.24% ± 22.11% [P = .024]).

Interestingly, levels of intestinal bifidobacteria and lactobacilli (including those related to Lactobacillus gasseri and Lactobacillus plantarum) were initially higher among infants with colic than in those without (14.57% ± 21.25% vs 4.45% ± 5.27% [P = .141] and 0.85% ± 1.17% vs 0.39% ± 0.39% [P = .232]).

By 1 and 2 weeks, however, the situation was reversed, with higher levels of these "good" bacteria seen among healthy infants (day 7, 13.46% ± 15.56% vs 29.64% ± 22.04% [P = .049] and 0.65% ± 1.30% vs 0.38% ± 0.67% [P = .529]; day 14, 31.85% ± 26.40% vs 24.69% ± 17.65% [P = .450] and 0.50% ± 0.74% vs 3.00% ± 3.30% [P = .023]).

Crying Linked to Gut Flora

After investigators controlled for breast-feeding, gender, birth weight, home vs hospital delivery, and sampling age in days multivariate analysis revealed an association between crying and higher levels of specific bacterial groups (particularly the proteobacteria) in early life, and by age 2 weeks the link between group differences in gut flora and crying became significant (P = .03).

Crying was positively associated with the presence of 8 bacterial groups, including the potentially pathogenic bacteria related to Escherichia, Klebsiella, Serratia, Vibrio, Yersinia, and Pseudomonas.

In contrast, crying was negatively linked to an abundance of bacteria belonging to the butyrate-producing species Butyrivibrio crossotus, Eubacterium rectale, and Eubacterium hallii, which were consistently found at 1.5-fold higher levels among healthy infants.

No associations were found between crying and other variables, such as sex, birth weight, breast-feeding, home/hospital delivery, and sampling age.

"The reduced diversity and specific microbiota signature observed in infants with colic already in the first weeks of age could suggest a role of microbiota development in the etiology of colic, as both well precede the usual colic peak," the authors write.

The study was supported by the Netherlands Organization for Scientific Research. The authors have disclosed no other relevant financial relationships.

Pediatrics. Published online January 14, 2013. Abstract

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