Abstract
BackgroundNewborn gastrointestinal (GI) tract is considered sterile but rapidly acquires a diverse microbiota from its intimate environment. Early acquisition of a bacterial species in the upper GI tract may play a role in establishing the colonic microbiota. There is paucity of molecular data on the upper GI tract microbiota in preterm neonates.MethodsGastric aspirates from 22 neonates with an average gestational age 27.7 weeks (±2.8), weighing 973.2 grams (±297.9) admitted to a neonatal intensive care unit were collected prospectively from weeks 1-4 of life. All samples were evaluated for microbiota using 16S rRNA-based Denaturing Gradient Gel Electrophoresis. Bacterial species colonization and its association with maternal and neonatal demographics, and neonatal clinical characteristics were analyzed.Results Bacteroides spp. was the predominant species in all four weeks. Bifidobacterium spp. colonization was significantly higher in exclusively breast milk fed compared to partially breast milk (PBM) fed neonates in first (p = 0.03) and third (p = 0.03) week of life. Anaerobic bacteria colonization decreased from first through fourth week of life (p = 0.03). Aerobic bacteria colonization was highly dynamic throughout the four week period. Premature rupture of membrane (p = 0.05) and birth outside of study hospital (p = 0.006) influenced the acquisition of bacteria in the first week of life. Birth weight was positively correlated with total number of bacterial species (p = 0.002) and anaerobes (p = 0.004) in PBM-fed neonates during the fourth week of life. H. pylori and Ureaplasma were not detected in any of our samples.ConclusionGastric bacterial colonization in preterm neonates is unstable during early weeks of life. Delayed oral feeding and use of antibiotics may be responsible for paucity of bacterial species. Monitoring of the gastric microbiota and concurrent examination of stool microbiota may yield important information on the utility of gastric signature patterns for predicting colon microbiota that may drive GI and immune dysfunctions.
Highlights
During the first two weeks in life, healthy full term neonates get colonized with a diverse and heterogeneous community of bacterial species, with Bifidobacteria predominating in breast-fed infants and a more mixed microbiota in those fed formula
Bifidobacterium spp. colonization was significantly higher in exclusively breast milk fed compared to partially breast milk (PBM) fed neonates in first (p = 0.03) and third (p = 0.03) week of life
Gastric bacterial colonization in preterm neonates is unstable during early weeks of life
Summary
During the first two weeks in life, healthy full term neonates get colonized with a diverse and heterogeneous community of bacterial species, with Bifidobacteria predominating in breast-fed infants and a more mixed microbiota in those fed formula. Recent studies using molecular techniques demonstrate that over 80% of the human intestinal tract bacteria are not detected by culture [9,10]. This suggests that the gastrointestinal tract microbial community still remains only partially explored. Recent molecular studies on stool microbiota during infancy suggest heterogeneity in bacterial profiles in early weeks of life [3,16]. There is paucity of molecular data on the upper GI tract microbiota in preterm neonates
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