Is house dust a reservoir for infant gut bacteria?

T Konya
University of Toronto: Master of Public Health

Numerous studies have identified an association between the infant gut microbiota and the development of asthma and atopic disease. Certain environmental exposures are known to shape the succession of infant gut microbiota; including birth delivery mode, antibiotic use, breast or formula feeding, and the mother’s own microbiota. This study investigates the extent to which the indoor environment itself may serve as a reservoir for gut bacteria. This study compared the microbiota of household dust with that of infant fecal samples collected at 3 months of age. Samples of infant stool and household dust were obtained for twenty 3-month-old infants from Winnipeg, Canada; these subjects were early recruits in the Canadian Healthy Infant Longitudinal Development (CHILD) study. For each sample, community bacterial 16S rDNA was sequenced using a novel Serial Illumina Sequencing (SI-seq) method. Summary and statistical analyses were performed using MS Excel, PC-ORD, and R on the full data set and a conserved data set that was reduced by an abundance cut-off. Both stool and dust samples were dominated by members of the phyla Actinobacteria, Firmicutes, and Proteobacteria with dust samples also having a large content of Cyanobacteria. Analysis by nonmetric dimensional scaling (NMDS) revealed dust and stool communities as 2 distinct groups. A modified permutation test revealed that the number of shared OTUs between dust and stool of the same subject was significantly higher than expected (p= 0.0328). The findings demonstrate a clear difference in the microbiomes of infant gut and household dust. However, the co-occurrence of select taxa in paired dust and stool samples suggests an association between the bacterial populations of these communities. Using a more conserved data set had minimal effect on the overall outcome of analyses.