Objective Asthma-like symptoms and eczema are common in childhood. Recent studies found airway pathogens to be involved in the development of asthma-like symptoms by inducing neutrophilic inflammation in the airway of wheezing infants. Staphylococcus aureus is reported to be associated with eczema in young children. Airway pathogens Haemophilus influenzae, Streptococcus pneumoniae, and/or Moraxella catarrhalis and skin pathogen S aureus are known to colonise the nasopharynx of healthy children. The relation between nasal colonisation of these pathogens and development of asthma-like symptoms and eczema in infancy remains unclear.

Methods We studied 1,079 infants in the Generation R Focus Study, a population-based prospective cohort study of pregnant women and their children. Nasal swabs for S aureus, H influenzae, S pneumoniae, and/or M catarrhalis cultures were obtained at 1.5, 6 and 14 months of age. Information on asthma-like symptoms and eczema was obtained from the age-adapted ISAAC questionnaire at 24 months. Details on confounding variables were obtained from questionnaires at 6, 12 and 24-month of age.

Results The prevalence of bacterial carriage change in the first years of life. S aureus carriage decreases, while the prevalence of S pneumoniae, M catarrhalis and H influenzae increases. Nasal colonisation with S aureus at 6 months is associated with eczema in the second year of life (aOR 2.59, 95% CI 1.50 to 4.45). Colonisation with one of the airway pathogens at 6 months is, after adjustment for gestational age and birthweight, associated with asthma-like symptoms in the second year of life (aOR 1.34, 95% CI 1.03 to 1.74).

Conclusion Bacterial carriage in infancy is a risk factor for asthma-like symptoms and eczema in childhood.