Diversity of the gut microbiota and eczema in early life

Abstract

Background: A modest number of prospective studies of the composition of the intestinal microbiota and eczema in early life have yielded conflicting results.

Objective: To examine the relationship between the bacterial diversity of the gut and the development of eczema in early life by methods other than stool culture.

Methods: Fecal samples were collected from 21 infants at 1 and 4 months of life. Nine infants were diagnosed with eczema by the age of 6 months (cases) and 12 infants were not (controls). After conducting denaturating gradient gel electrophoresis (DGGE) of stool samples, we compared the microbial diversity of cases and controls using the number of electrophoretic bands and the Shannon index of diversity (H') as indicators.

Results: Control subjects had significantly greater fecal microbial diversity than children with eczema at ages 1 (mean H' for controls = 0.75 vs. 0.53 for cases, P = 0.01) and 4 months (mean H' for controls = 0.92 vs. 0.59 for cases, P = 0.02). The increase in diversity from 1 to 4 months of age was significant in controls (P = 0.04) but not in children who developed eczema by 6 months of age (P = 0.32).

Conclusion: Our findings suggest that reduced microbial diversity is associated with the development of eczema in early life.

Figure 1

Denaturating gradient gel electrophoresis (DGGE). Stool samples were processed to extract 16S rDNA, the V2–V3 region was amplified by PCR, and denaturating gradient gel electrophoresis (DGGE) was performed using a standard protocol. For each lane, representing a single sample, the number of bands was counted and the Shannon index of diversity H' was calculated.

Figure 2

Number of bands and Shannon diversity index in all subjects. Controls had a higher number of bands at age 4 months (p = 0.06), and a higher Shannon index both at 1 (p = 0.01) and 4 months of age (p = 0.02).

Figure 3

Number of bands and Shannon diversity index by mode of delivery: Controls delivered vaginally had a higher Shannon index than cases at 1 month (p = 0.04) but not at 4 months; index for controls delivered by C-section was similar to cases at 1 month, but higher at 4 months (p = 0.04).

Figure 4

Predictions from mixed effects linear regression models. (Note: cases in red; controls in black). Number of bands: The increase in the number of bands tends to be more substantial in controls (p = 0.09) than in cases (p = 0.87); by age 4 months, controls have on average 2.6 bands more than cases. Shannon index: H' increases significantly in controls (p = 0.04) but not in cases (p = 0.32); at 1 month of age the index for controls is 0.22 higher, and at 4 months it is 0.33 higher. (*p < 0.05; see Table 1).