title: The impact of postnatal antibiotics on the preterm intestinal microbiome.
abstract: BACKGROUND
  Development of the intestinal microbiome in preterm infants has significant impact on infant health. Our objective was to determine if duration of antibiotics within the first 10 and 30 d after birth affects the intestinal microbiome.
  
  
  METHODS
  Subjects were 24 0/7-31 6/7 wk of gestational age who received ≥ 50% breast milk and a total of ≥ 100 ml/kg of feeds by 10 d. Rectal (fecal) swabs were collected at 10 and 30 d and analyzed by 16S rRNA pyrosequencing. At both time points, we examined the rectal microbiome from infants who received only 2 d of antibiotics and those who received at least 7 d of antibiotics.
  
  
  RESULTS
  In the 29 infants enrolled in our study, we found a decrease in diversity index from 10 d samples in those who received more antibiotics. Such difference in diversity and richness was not as pronounced in 30 d samples. Firmicutes and Bacteroidetes were most abundant in the 10 d samples. While these two phyla remained dominant in 30 d samples, there was an increase in Proteobacteria and Actinobacteria.
  
  
  CONCLUSIONS
  Despite antibiotic therapy, neonates continued to acquire bacteria in the gastrointestinal tract. The process of bacterial acquisition is perturbed with the use of antibiotics.
authors.affiliation: Division of Neonatology, Department of Pediatrics, University of Rochester Medical Center, Rochester, New York.
authors.forename: Majd
authors.initials: M
authors.lastname: Dardas
authors.affiliation: 1] Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York [2] Genomics Research Center, University of Rochester Medical Center, Rochester, New York.
authors.forename: Steven R
authors.initials: SR
authors.lastname: Gill
authors.affiliation: Genomics Research Center, University of Rochester Medical Center, Rochester, New York.
authors.forename: Alex
authors.initials: A
authors.lastname: Grier
authors.affiliation: Division of Neonatology, Department of Pediatrics, University of Rochester Medical Center, Rochester, New York.
authors.forename: Gloria S
authors.initials: GS
authors.lastname: Pryhuber
authors.affiliation: Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, New York.
authors.forename: Ann L
authors.initials: AL
authors.lastname: Gill
authors.affiliation: Division of Pediatric Surgery, Department of Surgery, University of Rochester Medical Center, Rochester, New York.
authors.forename: Yi-Horng
authors.initials: YH
authors.lastname: Lee
authors.affiliation: Division of Neonatology, Department of Pediatrics, University of Rochester Medical Center, Rochester, New York.
authors.forename: Ronnie
authors.initials: R
authors.lastname: Guillet
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology*; D001483:Base Sequence; D005243:Feces / Q000382:microbiology; D005260:Female; D041981:Gastrointestinal Tract / Q000187:drug effects / Q000382:microbiology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature; D064307:Microbiota / Q000187:drug effects*; D008969:Molecular Sequence Data; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents; D012336:RNA, Ribosomal, 16S