title: Nasal Airway Microbiota Profile and Severe Bronchiolitis in Infants: A Case-control Study.
abstract: BACKGROUND
  Little is known about the relationship of airway microbiota with bronchiolitis in infants. We aimed to identify nasal airway microbiota profiles and to determine their association with the likelihood of bronchiolitis in infants.
  
  
  METHODS
  A case-control study was conducted. As a part of a multicenter prospective study, we collected nasal airway samples from 40 infants hospitalized with bronchiolitis. We concurrently enrolled 110 age-matched healthy controls. By applying 16S ribosomal RNA gene sequencing and an unbiased clustering approach to these 150 nasal samples, we identified microbiota profiles and determined the association of microbiota profiles with likelihood of bronchiolitis.
  
  
  RESULTS
  Overall, the median age was 3 months and 56% were male. Unbiased clustering of airway microbiota identified 4 distinct profiles: Moraxella-dominant profile (37%), Corynebacterium/Dolosigranulum-dominant profile (27%), Staphylococcus-dominant profile (15%) and mixed profile (20%). Proportion of bronchiolitis was lowest in infants with Moraxella-dominant profile (14%) and highest in those with Staphylococcus-dominant profile (57%), corresponding to an odds ratio of 7.80 (95% confidence interval, 2.64-24.9; P < 0.001). In the multivariable model, the association between Staphylococcus-dominant profile and greater likelihood of bronchiolitis persisted (odds ratio for comparison with Moraxella-dominant profile, 5.16; 95% confidence interval, 1.26-22.9; P = 0.03). By contrast, Corynebacterium/Dolosigranulum-dominant profile group had low proportion of infants with bronchiolitis (17%); the likelihood of bronchiolitis in this group did not significantly differ from those with Moraxella-dominant profile in both unadjusted and adjusted analyses.
  
  
  CONCLUSIONS
  In this case-control study, we identified 4 distinct nasal airway microbiota profiles in infants. Moraxella-dominant and Corynebacterium/Dolosigranulum-dominant profiles were associated with low likelihood of bronchiolitis, while Staphylococcus-dominant profile was associated with high likelihood of bronchiolitis.
authors.affiliation: From the *Department of Emergency Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts; †Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia; ‡Department of Medicine, Boston Children's Hospital, Boston, Massachusetts; §Alkek Center for Metagenomics and Microbiome Research, Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas; ¶Department of Molecular Virology and Microbiology, and Pediatrics, Baylor College of Medicine, Houston, Texas; ‖Department of Pediatrics, University of Louisville, Louisville, Kentucky; and **Alfred I. duPont Hospital for Children, Wilmington, Delaware.
authors.forename: Kohei
authors.initials: K
authors.lastname: Hasegawa
authors.forename: Rachel W
authors.initials: RW
authors.lastname: Linnemann
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Mansbach
authors.forename: Nadim J
authors.initials: NJ
authors.lastname: Ajami
authors.forename: Janice A
authors.initials: JA
authors.lastname: Espinola
authors.forename: Joseph F
authors.initials: JF
authors.lastname: Petrosino
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Piedra
authors.forename: Michelle D
authors.initials: MD
authors.lastname: Stevenson
authors.forename: Ashley F
authors.initials: AF
authors.lastname: Sullivan
authors.forename: Amy D
authors.initials: AD
authors.lastname: Thompson
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Camargo
mesh_terms: D001424:Bacterial Infections / Q000453:epidemiology* / Q000382:microbiology*; D001988:Bronchiolitis / Q000453:epidemiology* / Q000382:microbiology*; D016022:Case-Control Studies; D016000:Cluster Analysis; D003352:Corynebacterium; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D009016:Moraxella; D009305:Nasopharynx / Q000382:microbiology*; D013210:Staphylococcus