title: Bacterial Colonization and Antibiotic Resistance in a Prospective Cohort of Newborn Infants During the First Year of Life.
abstract: BACKGROUND
  Infants are virtually sterile at birth and frequently use antibiotics; our objective was to (1) characterize the longitudinal colonization with bacterial pathogens and associated antibiotic resistance in a cohort of community-dwelling infants in Northeast Ohio and (2) describe longitudinal concurrent antibiotic and daycare exposures.
  
  
  METHODS
  For 35 newborns, nasopharyngeal swabs were cultured for Streptococcus pneumoniae, anterior nasal for Staphylococcus aureus, and perirectal for extended-spectrum beta-lactamase (ESBL)-producing Gram-negative enteric bacteria, at 3-month intervals for 12 months. Infant and household antibiotics and daycare exposure were assessed longitudinally.
  
  
  RESULTS
  Thirteen infants received perinatal or nursery antibiotics. By 3 months, at least 22 were colonized with Gram-negative bacteria; 2 with S pneumoniae (type 19A, resistant; 15C, susceptible), 5 with methicillin-susceptible S aureus. By 12 months, at least 22 of 35 infants received antibiotics, 20 had household members with antibiotics, and 12 attended daycare; 7 more had household members with daycare exposure. The ESBL-producing organisms were not identified. At least 10 infants were colonized at some time with an antibiotic-resistant organism, 3 more with pathogens displaying intermediate resistance. Pathogen colonization and resistance were intermittent and inconsistent.
  
  
  CONCLUSIONS
  In a community-based cohort followed from birth, early antibiotic and daycare exposures are common, especially considering perinatal maternal exposures. Colonization patterns of Gram-negative bacteria, S pneumoniae, S aureus, and resistant pneumococci are strikingly dynamic. Further research can identify key areas for potential interventions to maximize clinical antibiotic outcomes while minimizing future resistance.
authors.affiliation: Departments ofPediatrics,; Epidemiology and Biostatistics,; The Center for Child Health and Policy, Case Western Reserve University School of Medicine and Rainbow Babies and Children's Hospital, Cleveland, Ohio; and.
authors.forename: Sharon B
authors.initials: SB
authors.lastname: Meropol
authors.affiliation: Epidemiology and Biostatistics,; Family Medicine,; Oncology,; Sociology.
authors.forename: Kurt C
authors.initials: KC
authors.lastname: Stange
authors.affiliation: Pathology,; Medicine.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Jacobs
authors.affiliation: Family Medicine.
authors.forename: Judith K
authors.initials: JK
authors.lastname: Weiss
authors.affiliation: Pathology.
authors.forename: Saralee
authors.initials: S
authors.lastname: Bajaksouzian
authors.affiliation: Medicine,; Pharmacology, and; Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, Ohio;; Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, Ohio.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Bonomo
keywords: Staphylococcus; Streptococcus pneumonia.; antibacterial agents; drug resistance; infant