Respiratory infections in infants: the role of the microbiota

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Respiratory infections in infants may be influenced by the respiratory microbiota.

The quality of respiratory microbiota development plays a role in the risk of developing  respiratory infections during the first months of life, and is influenced by various environmental factors. This is what an English team showed. They analyzed the composition of the nasopharyngeal microbiota in 112 babies during their first year of life. They noted that the respiratory microbiota of children who experienced more episodes of respiratory infection during that period underwent an accelerated maturation process, compared with babies who were sick less often, and that several factors favored this acceleration: the presence of young brothers and sisters at home, group childcare, birth by Caesarean section, and formula feeding.
In infants who had suffered no more than two infectious episodes, Corynebacterium and Dolosigranulum spp. and then Moraxella were predominant in the first three months before the respiratory microbiota  stabilized. Vaginal delivery and breastfeeding during this phase of maturation promote the first two bacterial genera and the late predominance of Moraxella. Conversely, infants who had suffered at least three infectious episodes, presented a respiratory microbiota richer in Neisseria spp. and Prevotella spp., colonization by which is associated with formula feeding. Exposure to antibiotics also plays a role, particularly with a reduction in Corynebacterium and Dolosigranulum spp.

Source
Bosch AATM et al. Maturation of the Infant Respiratory Microbiota, Environmental Drivers and Health Consequences: A Prospective Cohort Study. Am J Respir Crit Care Med. 2017