title: Establishment of the intestinal microbiota and its role for atopic dermatitis in early childhood.
abstract: BACKGROUND
  Perturbations in the intestinal microbiota may disrupt mechanisms involved in the development of immunologic tolerance. The present study aimed to examine the establishment of the infant microbiota and its association to the development of atopic dermatitis (AD).
  
  
  METHODS
  Within a randomized, placebo-controlled trial on the prevention of AD by oral supplementation of a bacterial lysate between week 5 and the end of month 7, feces was collected at the ages of 5 weeks (n = 571), 13 weeks (n = 332), and 31 weeks (n = 499) and subjected to quantitative PCRs to detect bifidobacteria, bacteroides, lactobacilli, Escherichia coli, Clostridium difficile, and Clostridium cluster I.
  
  
  RESULTS
  Birth mode, breast-feeding but also birth order had a strong effect on the microbiota composition. With increasing number of older siblings the colonization rates at age 5 weeks of lactobacilli (P < .001) and bacteroides (P = .02) increased, whereas rates of clostridia decreased (P < .001). Colonization with clostridia, at the age of 5 and 13 weeks was also associated with an increased risk of developing AD in the subsequent 6 months of life (odds ratioadjusted = 2.35; 95% CI, 1.36-3.94 and 2.51; 1.30-4.86, respectively). Mediation analyses demonstrated that there was a statistically significant indirect effect via Clostridium cluster I colonization for both birth mode and birth order in association to AD.
  
  
  CONCLUSIONS
  The results of this study are supportive for a role of the microbiota in the development of AD. Moreover, the "beneficial" influence of older siblings on the microbiota composition suggests that this microbiota may be one of the biological mechanisms underlying the sibling effect.
authors.affiliation: Department of Medical Microbiology, School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, The Netherlands; Department of Epidemiology, School for Public Health and Primary Care, Maastricht University, Maastricht, The Netherlands. Electronic address: j.penders@maastrichtuniversity.nl.
authors.forename: John
authors.initials: J
authors.lastname: Penders
authors.affiliation: Department of Pediatric Pneumology and Immunology, Charité - Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Gerhold
authors.affiliation: Department of Medical Microbiology, School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Ellen E
authors.initials: EE
authors.lastname: Stobberingh
authors.affiliation: Department of Epidemiology, School for Public Health and Primary Care, Maastricht University, Maastricht, The Netherlands.
authors.forename: Carel
authors.initials: C
authors.lastname: Thijs
authors.affiliation: SymbioPharm, Herborn, Germany.
authors.forename: Kurt
authors.initials: K
authors.lastname: Zimmermann
authors.affiliation: Department of Pediatric Pneumology and Immunology, Charité - Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Lau
authors.affiliation: University Children's Hospital, Ruhr-Universität Bochum, Bochum, Germany.
authors.forename: Eckard
authors.initials: E
authors.lastname: Hamelmann
mesh_terms: D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification*; D058491:Bacterial Load; D001722:Birth Order; D001942:Breast Feeding; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D036861:Delivery, Obstetric; D003876:Dermatitis, Atopic / Q000175:diagnosis / Q000382:microbiology* / Q000517:prevention & control; D005243:Feces / Q000382:microbiology*; D005260:Female; D006801:Humans; D007223:Infant; D007422:Intestines / Q000382:microbiology*; D008297:Male; D011322:Primary Prevention
chemical_list: D004269:DNA, Bacterial
keywords: AD; Atopic dermatitis; C-section; CFU; Cesarean section; Colony-forming units; GI; Gastrointestinal; Microbiota; OR; Odds ratio; atopic dermatitis; birth mode; mediation analysis; siblings