title: Low diversity of the gut microbiota in infants with atopic eczema.
abstract: BACKGROUND
  It is debated whether a low total diversity of the gut microbiota in early childhood is more important than an altered prevalence of particular bacterial species for the increasing incidence of allergic disease. The advent of powerful, cultivation-free molecular methods makes it possible to characterize the total microbiome down to the genus level in large cohorts.
  
  
  OBJECTIVE
  We sought to assess microbial diversity and characterize the dominant bacteria in stool during the first year of life in relation to atopic eczema development.
  
  
  METHODS
  Microbial diversity and composition were analyzed with barcoded 16S rDNA 454-pyrosequencing in stool samples at 1 week, 1 month, and 12 months of age in 20 infants with IgE-associated eczema and 20 infants without any allergic manifestation until 2 years of age (ClinicalTrials.gov ID NCT01285830).
  
  
  RESULTS
  Infants with IgE-associated eczema had a lower diversity of the total microbiota at 1 month (P = .004) and a lower diversity of the bacterial phylum Bacteroidetes and the genus Bacteroides at 1 month (P = .02 and P = .01) and the phylum Proteobacteria at 12 months of age (P = .02). The microbiota was less uniform at 1 month than at 12 months of age, with a high interindividual variability. At 12 months, when the microbiota had stabilized, Proteobacteria, comprising gram-negative organisms, were more abundant in infants without allergic manifestation (Empirical Analysis of Digital Gene Expression in R [edgeR] test: P = .008, q = 0.02).
  
  
  CONCLUSIONS
  Low intestinal microbial diversity during the first month of life was associated with subsequent atopic eczema.
authors.affiliation: Department of Clinical and Experimental Medicine, Division of Pediatrics, Linköping University, Linköping, Sweden. thomas.abrahamsson@lio.se
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Abrahamsson
authors.forename: Hedvig E
authors.initials: HE
authors.lastname: Jakobsson
authors.forename: Anders F
authors.initials: AF
authors.lastname: Andersson
authors.forename: Bengt
authors.initials: B
authors.lastname: Björkstén
authors.forename: Lars
authors.initials: L
authors.lastname: Engstrand
authors.forename: Maria C
authors.initials: MC
authors.lastname: Jenmalm
mesh_terms: D000485:Allergens / Q000276:immunology; D001419:Bacteria / Q000145:classification / Q000235:genetics; D002675:Child, Preschool; D004269:DNA, Bacterial / Q000032:analysis; D004485:Eczema / Q000175:diagnosis / Q000382:microbiology* / Q000517:prevention & control; D005243:Feces / Q000382:microbiology; D005260:Female; D005512:Food Hypersensitivity / Q000097:blood / Q000175:diagnosis / Q000276:immunology; D006801:Humans; D006967:Hypersensitivity / Q000175:diagnosis / Q000382:microbiology* / Q000517:prevention & control; D007073:Immunoglobulin E / Q000097:blood; D007223:Infant; D007231:Infant, Newborn; D007422:Intestines / Q000382:microbiology*; D008297:Male; D019936:Probiotics / Q000627:therapeutic use; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D000485:Allergens; D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D007073:Immunoglobulin E