title: Trends and determinants of gastric bacterial colonization of preterm neonates in a NICU setting.
abstract: BACKGROUND
  Newborn 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.
  
  
  METHODS
  Gastric 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.
  
  
  CONCLUSIONS
  Gastric 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.
authors.affiliation: Department of Epidemiology, University of Nebraska Medical Center, College of Public Health, Omaha, NE, United States of America.
authors.forename: Ketki
authors.initials: K
authors.lastname: Patel
authors.affiliation: Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD, United States of America.
authors.forename: Kavitha
authors.initials: K
authors.lastname: Konduru
authors.affiliation: Department of Epidemiology, University of Nebraska Medical Center, College of Public Health, Omaha, NE, United States of America; Center for Global Health and Development, University of Nebraska Medical Center, College of Public Health, Omaha, NE, United States of America.
authors.forename: Alok K
authors.initials: AK
authors.lastname: Patra
authors.affiliation: Department of Environmental, Agricultural and Occupational Health, University of Nebraska Medical Center, College of Public Health, Omaha, NE, United States of America; Department of Pediatrics, University of Nebraska Medical Center, College of Public Health, Omaha, NE, United States of America; Center for Global Health and Development, University of Nebraska Medical Center, College of Public Health, Omaha, NE, United States of America.
authors.forename: Dinesh S
authors.initials: DS
authors.lastname: Chandel
authors.affiliation: Department of Epidemiology, University of Nebraska Medical Center, College of Public Health, Omaha, NE, United States of America; Department of Pediatrics, University of Nebraska Medical Center, College of Public Health, Omaha, NE, United States of America; Center for Global Health and Development, University of Nebraska Medical Center, College of Public Health, Omaha, NE, United States of America.
authors.forename: Pinaki
authors.initials: P
authors.lastname: Panigrahi
mesh_terms: D001419:Bacteria / Q000145:classification / Q000235:genetics; D044822:Biodiversity; D001724:Birth Weight; D020345:Enterocolitis, Necrotizing / Q000209:etiology; D000069196:Gastrointestinal Microbiome; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D007363:Intensive Care Units, Neonatal; D012336:RNA, Ribosomal, 16S
chemical_list: D012336:RNA, Ribosomal, 16S