Association between probiotics and bronchopulmonary dysplasia in preterm infants.

Bronchopulmonary dysplasia is a chronic pulmonary disease with a high incidence in premature infants, and there is still no effective treatment. The purpose of our study was to analyze the association between the use of probiotics and BPD in premature infants. We retrospectively collected clinical data of infants with gestational age < 32 weeks admitted to the NICU of The First Hospital of Jilin University from January 1, 2019 to March 31, 2020. Demographic and clinicopathological data of the inclusion population were collected. The outcome was the incidence of BPD or death. The χ2 tests was used to compare the categorical variables. The t test and non-parametric Wilcoxon rank-sum test were used to compare the continuous data. Univariate and multivariate logistic regression were used to analyze the association between probiotics and BPD. A total of 318 newborns met the inclusion criteria, of which 94 received probiotics and 224 received no probiotics. There were 16 deaths and 115 newborns with BPD in the included population. The results of univariate analysis showed differences in the maternal diabetes, the proportion of systemic antibiotics given to mother within 24 h before birth, the receiving rate of invasive mechanical ventilation, the prevalence of BPD/death, PDA, RDS and Ivh between newborns with and without probiotics (p < 0.05); The results of unadjusted univariate logistic regression model showed that probiotic (OR 0.034, 95% CI 0.012-0.096) was the factor affecting BPD in preterm infants (p < 0.05). Multivariate logistic regression result (OR 0.037, 95% CI 0.013-0.105) was consistent with univariate analysis (P < 0.001). Probiotics are associated with a reduced risk of BPD in preterm infants < 32 weeks of age. More prospective studies with large samples are still needed.

Early Gut Microbiota Changes in Preterm Infants with Bronchopulmonary Dysplasia: A Pilot Case-Control Study.

OBJECTIVE: Bronchopulmonary dysplasia (BPD) is a complex chronic lung disease that primarily affects premature or critically ill infants. This pilot study investigated early changes in gut microbiota composition in BPD patients and explored the potential risk factors associated with these changes. STUDY DESIGN: Preterm infants admitted to our neonatal intensive care unit with a gestational age of 26 to 32 weeks were prospectively surveyed and eligible for stool collection on days 7 and 28 of postnatal age between February 2016 and June 2017. A 16S rRNA sequencing approach was applied to compare the gut microbiota composition between the BPD group and controls. Multiple linear regression analysis was used to identify the predictor variables. RESULTS: Eight subjects in the BPD group and 10 subjects in the preterm group were analyzed during the observation period. Actinobacteria, Proteobacteria, Bacteroidetes, and Firmicutes were the four dominant bacteria phyla of intestinal microflora. A significantly lower diversity of gut microbiota was observed in the BPD group compared with the preterm group on day 28 (number of observed operational taxonomic units, p = 0.034; abundance-based coverage estimator, p = 0.022; Shannon index, p = 0.028). Multiple linear regression analysis revealed that high Neonatal Therapeutic Intervention Scoring System score (≧19) at 24 hours was statistically significant in predicting the proportion of aerobic with facultative anaerobic bacteria on day 28 (p = 0.002). CONCLUSION: Infants with BPD are prone to develop gut dysbiosis in early life. A higher severity of illness and treatment intensity may indicate a higher risk of disrupting an anaerobic environment in the gut during the first month of life. KEY POINTS: · BPD patients are prone to develop gut dysbiosis.. · Lower diversity of gut microbiota.. · Higher risk of disrupting anaerobic environment..

The association between the microbes in the tracheobronchial aspirate fluid and bronchopulmonary dysplasia in preterm infants.

OBJECTIVE: The study aimed to evaluate the association between microbes in the lower respiratory tract (LRT) and the srisk for severe bronchopulmonary dysplasia (sBPD) in premature infants. METHODS: We conducted a retrospective, single-center study of preterm infants who were admitted to the neonatal intensive care unit (NICU) of Southern Medical University Affiliated Maternal & Child Health Hospital of Foshan, China, between January 2015 and December 2017. The microbes in the LRT were screened by using tracheobronchial aspirate fluid (TAF) culture. RESULTS: One hundred and fifty-five infants were included in the analysis. Among 155 infants, 41 were diagnosed with sBPD, and 114 were diagnosed without sBPD. There were significant differences between infants with and without sBPD in regard to birth weight (BW), gestational age (GA), the duration of endotracheal ventilation and supplemental oxygen. The incidence of retinopathy (ROP) and sepsis was higher in the sBPD infants than in the infants without sBPD. There was a difference in the detection rate of Gram-negative bacteria (GNB) between the two groups. Stenotrophomonas maltophilia and Klebsiella pneumoniae were mainly detected in TAF. CONCLUSIONS: The LRT microbes were different between infants with and without sBPD, and GNB is more frequently detected in sBPD infants.

Dissimilarity of the gut-lung axis and dysbiosis of the lower airways in ventilated preterm infants.

BACKGROUND: Chronic lung disease of prematurity (CLD), also called bronchopulmonary dysplasia, is a major consequence of preterm birth, but the role of the microbiome in its development remains unclear. Therefore, we assessed the progression of the bacterial community in ventilated preterm infants over time in the upper and lower airways, and assessed the gut-lung axis by comparing bacterial communities in the upper and lower airways with stool findings. Finally, we assessed whether the bacterial communities were associated with lung inflammation to suggest dysbiosis. METHODS: We serially sampled multiple anatomical sites including the upper airway (nasopharyngeal aspirates), lower airways (tracheal aspirate fluid and bronchoalveolar lavage fluid) and the gut (stool) of ventilated preterm-born infants. Bacterial DNA load was measured in all samples and sequenced using the V3-V4 region of the 16S rRNA gene. RESULTS: From 1102 (539 nasopharyngeal aspirates, 276 tracheal aspirate fluid, 89 bronchoalveolar lavage, 198 stool) samples from 55 preterm infants, 352 (32%) amplified suitably for 16S RNA gene sequencing. Bacterial load was low at birth and quickly increased with time, but was associated with predominant operational taxonomic units (OTUs) in all sample types. There was dissimilarity in bacterial communities between the upper and lower airways and the gut, with a separate dysbiotic inflammatory process occurring in the lower airways of infants. Individual OTUs were associated with increased inflammatory markers. CONCLUSIONS: Taken together, these findings suggest that targeted treatment of the predominant organisms, including those not routinely treated, such as Ureaplasma spp., may decrease the development of CLD in preterm-born infants.

Metabolomics of bronchopulmonary dysplasia.

The pathogenesis of Bronchopulmonary dysplasia (BPD) remains poorly understood. It is a multifactorial disease having a genetic-environmental basis. Although attempts have been made to identify a biomarker, none have been validated for clinical use to date. Metabolomics is a promising field of the "omics technologies" that could allow for better understanding of the pathogenesis and underlying mechanisms of BPD as well as facilitate detection of biomarkers. Identification of these biomarkers would improve diagnosis, identify patients in early disease stages and potentially target intervention. This review focuses on the evidence arising from metabolomics and its interaction with microbiomics and pharmacology with respect to pathogenesis and treatment options for this multifactorial complex disease.

Broad spectrum antibiotics in newborns increase multi-drug resistant infections.

Our objective was to determine if broad spectrum antibiotics (BSA) are associated with multi-resistant bacterial (MRB) infections in neonatal patients. We conducted a case-control study with two groups of patients: those with and without a MRB infection. We included 43 cases and 43 controls. MRB strains were: 21 S. maltophila (49%), 11 ESBL-producing Enterobacteriae (25%), 8 P. aeruginosa (19%) and 3 MRSA (7%). Odds ratio (OR) for MRB after seven days of carbapenems was 4.25 (95% confidence interval (CI) 1.4-17.4) and OR for MRB after seven days of third generation cephalosporin was 8 (95% CI 1.1-34.9). BSA longer than seven days, increases MRB infections 22.5 times in patients with bronchopulmonary dysplasia (BPD). Our data show a clear association between the use of BSA and the development of MRB infections, especially in BPD. Although we cannot state this is a causal relationship, we can recommend avoiding prolonged treatment with these antibiotics in preterm babies at risk of BPD.

The lung microbiome in neonates.

Permall DL, Pasha AB, Chen XQ, Lu HY. The lung microbiome in neonates. Turk J Pediatr 2019; 61: 821-830. Despite the advent of culture-independent techniques to identify members of the microbiome, studies focusing on the lung microbiome of neonates are scarce. Understanding the role of the microbiome in the pathogenesis of pulmonary conditions affecting newborns could lead to the initiation of pioneering therapeutic interventions, which could potentially prevent lifelong disability. Bronchopulmonary dysplasia (BPD) has been associated with a less diverse microbiome, presence of Ureaplasma species and reduced Lactobacillus detection. Additionally, the potential role of microbial dysbiosis in the pathogenesis of asthma, cystic fibrosis and pneumonia has been described. There has also been a surge of interest in attempting to elucidate the interactions between the airway and gut microbiomes and their bearings on respiratory health and diseases to eventually broaden the scope of therapeutic interventions.

Airway microbiome in adult survivors of extremely preterm birth: the EPICure study.

Bronchopulmonary dysplasia (BPD) is a major complication of preterm birth that leads to lifelong respiratory morbidity. The EPICure study has investigated the longitudinal health outcomes of infants born extremely preterm (EP; <26 weeks gestation). Our aim was to characterise the airway microbiome in young adults born extremely preterm, with and without neonatal BPD, in comparison to matched term-born controls.Induced sputum was collected from 92 young adults aged 19 years (51 EP and 41 controls). Typical respiratory pathogens were detected using quantitative PCR. 16S rRNA gene sequencing was completed on 74 samples (29 EP with BPD; 9 EP without BPD; and 36 controls).The preterm group with BPD had the least diverse bacterial communities. The relative abundance of Bacteriodetes, particularly Prevotella melaninogenica was significantly lower in the preterm group compared to controls. This decline was balanced by a nonsignificant increase in Firmicutes. Total Prevotella relative abundance correlated with forced expiratory volume in 1 s z-score (ρ=0.272; p<0.05). Typical respiratory pathogen loads and prevalence were similar between groups.In conclusion, extremely preterm birth is associated with a significant dysbiosis in airway microbiome in young adulthood regardless of neonatal BPD status. This is characterised by a shift in the community composition away from Bacteriodetes as manifested in a significant drop in Prevotella relative abundance.

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

OBJECTIVES: To summarize evidence regarding microbial dysbiosis of the airway associated with bronchopulmonary dysplasia (BPD) and to explore heterogeneity among studies. STUDY DESIGN: 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. RESULTS: 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. CONCLUSIONS: 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.

Bronchoscopy in neonates with severe bronchopulmonary dysplasia in the NICU.

OBJECTIVES: To describe the findings, resulting changes in management, and safety profile of flexible bronchoscopy in the neonates with severe bronchopulmonary dysplasia. STUDY DESIGN: This was a retrospective case series of twenty-seven neonates with severe bronchopulmonary dysplasia who underwent flexible bronchoscopy in the neonatal intensive care unit. RESULTS: Flexible bronchoscopy revealed airway pathology in 20/27 (74%) patients. Tracheomalacia 13/27 (48%), bronchomalacia 11/27 (40.7%), and airway edema 13/27 (48%) were the most common findings. Bronchoalveolar lavage (BAL) was performed in 17 patients. BAL culture revealed a microorganism in 12/17 (70.5%) cases. Findings from bronchoscopy resulted in change in clinical management in 17/27 (63%) patients. Common interventions included initiation of antibiotics (37%) and treatment of tracheobronchomalacia with bethanechol (22.2%), atrovent (18.5%), and PEEP titration (18.5%). Bronchoscopy was performed without significant complication in 26/27 (97%) patients. CONCLUSION: Flexible bronchoscopy can be a safe and useful tool for the management of neonates with severe bronchopulmonary dysplasia.

Different degrees of maternal Ureaplasma colonization and its correlation with bronchopulmonary dysplasia in <32 weeks' preterm infants.

BACKGROUND: Ureaplasma spp. is a known risk factor for bronchopulmonary dysplasia (BPD). However, little is known about the effect of different degrees of maternal Ureaplasma colonization and their adverse outcomes. Hence, the aim of this study was to determine the effects of different degrees of maternal Ureaplasma colonization on BPD. METHODS: A retrospective cohort study of preterm infants delivered at <32 weeks' gestational age (GA) was performed. The infants were divided according to maternal Ureaplasma status as follows: high-colonization (≥104 CCU/ml, UUH), low-colonization (<104 CCU/ml, UUL), and noncolonization (controls). Subgroup analysis according to neonatal respiratory Ureaplasma (n-UU) was also performed to evaluate vertical transmission. RESULTS: In total, 245 infants were included in this study (UUH = 105, UUL = 47, controls = 93). The rates of preterm labor and histological chorioamnionitis were significantly different. The rate of BPD was significantly high in UUH (P = 0.044). The transmission rate of n-UU colonization was 36% in UUH and 32% in UUL (P = 0.609). The rate of BPD was 78% in n-UU (+) of UUH but 43% in n-UU (-) of UUL (P = 0.027). CONCLUSIONS: High-degree colonization of maternal Ureaplasma was associated with preterm labor, histological chorioamnionitis, and neonatal BPD. The incidence of BPD was significantly higher in Ureaplasma-colonized infants born to women with high-degree colonization.

Early airway microbial metagenomic and metabolomic signatures are associated with development of severe bronchopulmonary dysplasia.

The pathogenesis of bronchopulmonary dysplasia (BPD) is not well understood. We previously identified differences in the airway microbiome at birth between preterm infants who were BPD predisposed versus those who were BPD resistant. In this study, we attempted to identify mechanisms by which the airway microbiome could modify the risk for BPD. We used a software-based method to predict the metagenome of the tracheal aspirate (TA) microbiome from 16S rRNA sequencing data in preterm infants and to identify functional ortholog genes that were differentially abundant in BPD-predisposed and BPD-resistant infants. We also identified metabolites that were differentially enriched in these samples by use of untargeted mass spectrometry and mummichog to identify the metabolic pathways involved. Microbial metagenome analysis identified specific pathways that were less abundant in the functional metagenome of the microbiota of BPD-predisposed infants compared with BPD-resistant infants. The airway metabolome of BPD-predisposed infants was enriched for metabolites involved in fatty acid activation and androgen and estrogen biosynthesis compared with BPD-resistant infants. These findings suggest that in extremely preterm infants the early airway microbiome may alter the metabolome, thereby modifying the risk of BPD. The differential enrichment of sex steroid metabolic pathways supports previous studies suggesting a role for sexual dimorphism in BPD risk. This study also suggests a role for metabolomic and metagenomic profiles to serve as early biomarkers of BPD risk.

Beyond sepsis: Staphylococcus epidermidis is an underestimated but significant contributor to neonatal morbidity.

Staphylococcus epidermidis accounts for the majority of cases of neonatal sepsis. Moreover, it has been demonstrated to be associated with neonatal morbidities, such as bronchopulmonary dysplasia (BPD), white matter injury (WMI), necrotizing enterocolitis (NEC) and retinopathy of prematurity (ROP), which affect short-term and long-term neonatal outcome. Imbalanced inflammation has been considered to be a major underlying mechanism of each entity. Conventionally regarded as a harmless commensal on human skin, S. epidermidis has received less attention than its more virulent relative Staphylococcus aureus. Particularities of neonatal innate immunity and nosocomial environmental factors, however, may contribute to the emergence of S. epidermidis as a significant nosocomial pathogen. Neonatal host response to S. epidermidis sepsis has not been fully elucidated. Evidence is emerging regarding the implication of S. epidermidis sepsis in the pathogenesis of neonatal inflammatory diseases. This review focuses on the interplay among S. epidermidis, neonatal innate immunity and inflammation-driven organ injury.

Airway Microbial Community Turnover Differs by BPD Severity in Ventilated Preterm Infants.

Preterm birth exposes the developing lung to an environment with direct exposure to bacteria, often facilitated by endotracheal intubation. Despite evidence linking bacterial infections to the pathogenesis of bronchopulmonary dysplasia (BPD), systematic studies of airway microbiota are limited. The objective was to identify specific patterns of the early respiratory tract microbiome from tracheal aspirates of mechanically ventilated preterm infants that are associated with the development and severity of BPD. Infants with gestational age ≤34 weeks, and birth weight 500-1250g were prospectively enrolled. Mechanically ventilated infants had tracheal aspirate samples collected at enrollment, 7, 14, and 21 days of age. BPD was determined by modified NIH criteria with oxygen reduction tests; infants without BPD were excluded due to low numbers. Aspirates were processed for bacterial identification by 16S rRNA sequencing, and bacterial load by qPCR. Cross-sectional analysis was performed using 7 day samples and longitudinal analysis was performed from subjects with at least 2 aspirates. Microbiome analysis was performed on tracheal aspirates from 152 infants (51, 49, and 52 with mild, moderate, and severe BPD, respectively). Seventy-nine of the infants were included in the cross-sectional analysis and 94 in the longitudinal. Shannon Diversity, bacterial load, and relative abundance of individual taxa were not strongly associated with BPD status. Longitudinal analysis revealed that preterm infants who eventually developed severe BPD exhibited greater bacterial community turnover with age, acquired less Staphylococcus in the first days after birth, and had higher initial relative abundance of Ureaplasma. In conclusion, longitudinal changes in the airway microbial communities of mechanically ventilated preterm infants may be associated with BPD severity, whereas cross-sectional analysis of airway ecology at 7 days of age did not reveal an association with BPD severity. Further evaluation is necessary to determine whether the observed longitudinal changes are causal or in response to clinical management or other factors that lead to BPD.

Coexistence of Ureaplasma and chorioamnionitis is associated with prolonged mechanical ventilation.

BACKGROUND: Both histologic chorioamnionitis (HCAM) and Ureaplasma infection are considered important contributors to perinatal lung injury. We tested the hypothesis that coexistence of maternal HCAM and perinatal Ureaplasma exposure increases the risk of prolonged mechanical ventilation in extremely low-birthweight (ELBW) infants. METHODS: A retrospective cohort study was carried out of all ELBW infants born between January 2008 and December 2013 at a single academic center. Placental pathology and gastric fluid Ureaplasma data were available for all infants. Culture and polymerase chain reaction were used to detect Ureaplasma in gastric fluid. Prolonged mechanical ventilation was defined as mechanical ventilation that began within 28 days after birth and continued. RESULTS: Of 111 ELBW infants enrolled, 84 survived beyond 36 weeks of postmenstrual age (PMA) and were included in the analysis. Eighteen infants (21.4%) had both HCAM and Ureaplasma exposure. Seven infants (8.3%) required mechanical ventilation beyond 36 weeks of PMA. Coexistence of HCAM and Ureaplasma in gastric fluid was significantly associated with prolonged mechanical ventilation after adjustment for gestational age, sex, mode of delivery, and use of macrolide antibiotics (OR, 8.7; 95%CI: 1.1-67.2). CONCLUSIONS: Coexistence of maternal HCAM and perinatal Ureaplasma exposure significantly increases the risk of prolonged mechanical ventilation in ELBW infants.

Cellular and humoral biomarkers of Bronchopulmonary Dysplasia.

The pathogenesis of Bronchopulmonary Dysplasia (BPD) is multifactorial and the clinical phenotype of BPD is extremely variable. Predicting BPD is difficult, as it is a disease with a clinical operational definition but many clinical phenotypes and endotypes. Most biomarkers studied over the years have low predictive accuracy, and none are currently used in routine clinical care or shown to be useful for predicting longer-term respiratory outcome. Targeted cellular and humoral biomarkers and novel systems biology 'omic' based approaches including genomic and microbiomic analyses are described in this review.

The Microbiome of the Lower Respiratory Tract in Premature Infants with and without Severe Bronchopulmonary Dysplasia.

Aim We determined whether the bacteria in the lower respiratory tract (LRT) in extremely premature infants with severe bronchopulmonary dysplasia (BPD) are different from those with nonsevere BPD. Study Design We conducted a retrospective study of extremely premature infants who were admitted to the neonatal intensive care unit of Fukushima Medical University Hospital, Japan between April 2005 and March 2014. We screened for the bacterial colonization of the LRT using tracheobronchial aspirate fluid. Results A total of 169 extremely premature infants were included. Overall, 102 did not experience severe BPD, whereas the remaining 67 experienced severe BPD. Corynebacterium species (Cs) were more frequently detected in the severe BPD than nonsevere BPD infants (p = 0.03). There were significant differences between infants with and without severe BPD in the duration of endotracheal ventilation (p = 0.00, odds ratio [OR], 1.03; 95% confidence interval [CI], 1.01-1.06), the duration of supplemental oxygen (p = 0.00, OR, 1.02; 95% CI, 1.01-1.03) before 36 weeks of postmenstrual age, and the frequency of sepsis after 7 postnatal days (p = 0.01, OR, 1.73; 95% CI, 1.18-2.54). Conclusion Cs are more likely to be present in the severe BPD infants with longer duration of endotracheal ventilation.

Role of Ureaplasma Respiratory Tract Colonization in Bronchopulmonary Dysplasia Pathogenesis: Current Concepts and Update.

Respiratory tract colonization with the genital mycoplasma species Ureaplasma parvum and Ureaplasma urealyticum in preterm infants is a significant risk factor for bronchopulmonary dysplasia (BPD). Recent studies of the ureaplasmal genome, animal infection models, and human infants have provided a better understanding of specific virulence factors, pathogen-host interactions, and variability in genetic susceptibility that contribute to chronic infection, inflammation, and altered lung development. This review provides an update on the current evidence supporting a causal role of ureaplasma infection in BPD pathogenesis. The current status of antibiotic trials to prevent BPD in Ureaplasma-infected preterm infants is also reviewed.

Macrolides do not affect the incidence of moderate and severe bronchopulmonary dysplasia in symptomatic ureaplasma-positive infants.

AIM: The aim of this study was to compare the incidence of bronchopulmonary dysplasia (BPD) in symptomatic ureaplasma-positive treated preterm infants and asymptomatic preterm infants not tested or treated for ureaplasma. METHODS: A retrospective matched cohort study was conducted in a tertiary, neonatal unit between January 2007 and December 2012. Infants ≤29 completed weeks with signs and symptoms suggesting ureaplasma pneumonia who received macrolides comprised the study group. Infants ≤29 weeks without signs and symptoms not tested or treated with macrolides were the controls. Infants were mandatorily matched for gestational age ± one week or birthweight ± 100 grams. RESULTS: There were 31 infants in the study group and 62 in the control group. The baseline demographic data of both groups were similar on the whole. The incidence of moderate and severe BPD, defined by oxygen dependency or the need for continuous positive airway pressure at 36 weeks of postconceptual age, was 45.2% in the study group and 40.3% in the controls (p = 0.65). There was no significant difference in morbidities or mortality between the groups. CONCLUSION: A selective approach of treating symptomatic ureaplasma-positive preterm infants with macrolides did not affect the incidence of moderate and severe BPD.

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-1ß, IL-6, IL-8, IL-10, and IL-12), tumor necrosis factor-α, interferon-γ, 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.