title: The loss of topography in the microbial communities of the upper respiratory tract in the elderly.
abstract: BACKGROUND
  The microbial communities inhabiting the upper respiratory tract protect from respiratory infection. The maturity of the immune system is a major influence on the composition of the microbiome and, in youth, the microbiota and immune system are believed to mature in tandem. With age, immune function declines and susceptibility to respiratory infection increases. Whether these changes contribute to the microbial composition of the respiratory tract is unknown.
  
  
  OBJECTIVE
  Our goal was to determine whether the microbes of the upper respiratory tract differ between mid-aged adults (18-40 yr) and the elderly (>65 yr).
  
  
  METHODS
  Microbiomes of the anterior nares and oropharynx of elderly individuals were evaluated by 16S rRNA gene sequencing. These communities were compared with data on mid-aged adults obtained from the Human Microbiome Project.
  
  
  RESULTS
  The microbiota of the elderly showed no associations with sex, comorbidities, residence, or vaccinations. Comparisons of mid-aged adults and the elderly demonstrated significant differences in the composition of the anterior nares and oropharynx, including a population in the anterior nares of the elderly that more closely resembled the oropharynx than the anterior nares of adults. The elderly oropharyngeal microbiota were characterized by increased abundance of streptococci, specifically, Streptococcus salivarius group species, but not Streptococcus pneumoniae, carriage of which was low (<3% of participants), as demonstrated by PCR (n = 4/123).
  
  
  CONCLUSIONS
  Microbial populations of the upper respiratory tract in mid-aged adults and the elderly differ; it is possible that these differences contribute to the increased risk of respiratory infections experienced by the elderly.
authors.affiliation: 1 Department of Biochemistry and Biomedical Sciences.
authors.forename: Fiona J
authors.initials: FJ
authors.lastname: Whelan
authors.forename: Chris P
authors.initials: CP
authors.lastname: Verschoor
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Stearns
authors.forename: Laura
authors.initials: L
authors.lastname: Rossi
authors.forename: Kathy
authors.initials: K
authors.lastname: Luinstra
authors.forename: Mark
authors.initials: M
authors.lastname: Loeb
authors.forename: Marek
authors.initials: M
authors.lastname: Smieja
authors.forename: Jennie
authors.initials: J
authors.lastname: Johnstone
authors.forename: Michael G
authors.initials: MG
authors.lastname: Surette
authors.forename: Dawn M E
authors.initials: DM
authors.lastname: Bowdish
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D004269:DNA, Bacterial / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D064307:Microbiota / Q000235:genetics* / Q000276:immunology; D009296:Nasal Cavity / Q000276:immunology / Q000382:microbiology*; D009960:Oropharynx / Q000276:immunology / Q000382:microbiology*; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics*; D012141:Respiratory Tract Infections / Q000276:immunology / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D013291:Streptococcus / Q000235:genetics*; D013296:Streptococcus pneumoniae / Q000235:genetics; D055815:Young Adult
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S