Airway Microbiome and Development of Bronchopulmonary Dysplasia in Preterm Infants: A Systematic Review

To summarize evidence regarding microbial dysbiosis of the airway associated with bronchopulmonary dysplasia (BPD) and to explore heterogeneity among studies. We included studies that evaluated the airway microbiome in preterm infants who developed BPD using culture-independent molecular techniques and reported alpha- and beta-diversity metrics and microbial profiles. The 6 included studies had substantial clinical and methodological heterogeneity. Most studies reported the presence of an airway microbiome early after birth and an evolution in the first weeks of life with increasing bacterial loads. The early airway microbiome was dominated by Staphylococcus and Ureaplasma spp. Two studies reported differences in alpha- and beta- diversity indices in preterm infants with BPD compared with those who did not develop BPD. Increased microbial community turnover, changes in the relative abundance of Proteobacteria and Firmicutes, and decreased Lactobacilli were reported with BPD progression. Most included infants were born by cesarean delivery, and a majority were exposed to postnatal antibiotics. No data regarding feeding human milk or correlations with the development of gut microbiota (gut-lung axis) were available. Microbial dysbiosis may be associated with BPD progression and severity, and further study of microbiome optimization in preterm infants at risk for BPD is warranted.