Indoor microbial environment and asthma outcomes in childhood

Abstract

While the indoor environment in early life is thought to play a role in asthma development, the effects of exposure to specific microorganisms according to the timing of exposure need to be clarified. We investigated the associations between exposure to indoor microorganisms using electrostatic dust collectors (EDC), installed in the child’s bedroom, and real-time quantitative PCR (qPCR) at birth and age 5 years, and asthma outcomes in 3187 children from the French ELFE birth cohort. Microbial exposure was quantified when the child was <1 month (n = 3193 EDC) and again at 5 years (n = 1773 EDC) using 16 qPCR targets (molds, bacteria groups, mites and pets). Associations with wheezing and asthma at 1 and 5 years were evaluated by logistic regression, adjusting for potential confounders. Wheezing at 12 months was found in 29% children. Associations with exposure at birth showed a positive association for Dermatophagoïdes pteronyssinus (odds ratio (95% CI) = 1.36 (1.10; 1.68) comparing highest to lowest quartile, p for trend=0.005). Weak positive trends were also identified for Alternaria alternata, Cladosporium sphaerospermum, Mycobacteria, Streptomyces spp. and dog. Weaker associations were observed when considering birth exposure and symptoms at 5 years, although dog exposure was still associated with more wheeze at 5 years. Different patterns of associations were observed when considering exposure at age 5. Our first results suggest that allergenic, fungal and bacterial exposure in early life may be associated with more wheeze at one year and probably also at 5 years. Analyses are continuing in order to disentangle the effects of the multifactorial determinants of indoor microbial exposure.