The nasal microbiome in early infancy is primarily shaped by the maternal nasal microbiome.

Abstract

BACKGROUND The infant nasal microbiota closely mediates the risks of developing childhood respiratory diseases. However, the primary sources of these early residing bacteria remain largely unknown, preventing the development of microbiome strategies for disease prevention. OBJECTIVE Identify the primary maternal source of bacteria found in the early infant nasal microbiome. METHODS We conducted a birth cohort study, named Mother Infant Microbiome International Cohort (MIMIC). We recruited 95 mother-newborn dyads from three sites (St. Louis, Missouri, United States; San Juan, Puerto Rico; and Accra, Ghana) and collected samples at two time points (at birth and around two months of age). We performed analyses on 16S ribosomal RNA gene sequencing data to evaluate the maternal microbiomes (nasal, saliva, breast milk, and areola skin) as sources seeding the infant nasal microbiome. RESULTS The infant nasal microbiome underwent a major compositional change during the first two months of life. The maternal nasal microbiome was identified as the primary source of bacteria in the early nasal microbiome across the three regions. Corynebacterium was predominantly transferred from the maternal nasal microbiome. Infants were more likely to harbor a Corynebacterium-dominant nasal microbiome if their mother's nasal microbiome was Corynebacterium-dominant. CONCLUSIONS The maternal nasal microbiome is an important source of bacteria in the early nasal microbiome. A large portion of transmitted bacteria from the maternal nasal microbiome was a generally beneficial bacterial genus, Corynebacterium. Results from this study will aid the development of early life intervention strategies that aim to reduce the incidence of childhood respiratory diseases and asthma.