The airway microbiome of intubated premature infants: characteristics and changes that predict the development of bronchopulmonary dysplasia

BACKGROUND: Bronchopulmonary dysplasia (BPD) is associated with perinatal inflammatory triggers. Methods targeting bacterial rRNA may improve detection of microbial colonization in premature infants. We hypothesize that respiratory microbiota differs between preterm infants who develop BPD and those unaffected and correlates with inflammatory mediator concentrations. METHODS: Twenty-five infants, born at <= 32 wk of gestation and intubated in the first 24 h, were enrolled. Tracheal aspirates were obtained at intubation and on days 3, 7, and 28. Bacterial DNA was extracted, and 16S rRNA genes were amplified and sequenced. Concentrations of interleukins (IL-1 beta, IL-6, IL-8, IL-10, and IL-12), tumor necrosis factor-alpha, interferon-gamma, lipopolysaccharide (LPS), and lipoteichoic acid (LTA) were measured. Chorioamnionitis was diagnosed by histology. BPD was defined as an oxygen requirement at 36 wk postmenstrual age. RESULTS: Acinetobacter was the predominant genus in the airways of all infants at birth. Ten infants developed BPD and showed reduced bacterial diversity at birth. No differences were detected in bacterial diversity, cytokines, LPS, and LTA from infants with and without exposure to chorioamnionitis. CONCLUSION: The airways of premature infants are not sterile at birth. Reduced diversity of the microbiome may be an important factor in the development of BPD and is not associated with differences in inflammatory mediators.