Abstract
BackgroundInfection by pathogenic viruses results in rapid epithelial damage and significantly impacts on the condition of the upper respiratory tract, thus the effects of viral infection may induce changes in microbiota. Thus, we aimed to define the healthy microbiota and the viral pathogen-affected microbiota in the upper respiratory tract. In addition, any association between the type of viral agent and the resultant microbiota profile was assessed.MethodsWe analyzed the upper respiratory tract bacterial content of 57 healthy asymptomatic people (17 health-care workers and 40 community people) and 59 patients acutely infected with influenza, parainfluenza, rhino, respiratory syncytial, corona, adeno, or metapneumo viruses using culture-independent pyrosequencing.ResultsThe healthy subjects harbored primarily Streptococcus, whereas the patients showed an enrichment of Haemophilus or Moraxella. Quantifying the similarities between bacterial populations by using Fast UniFrac analysis indicated that bacterial profiles were apparently divisible into 6 oropharyngeal types in the tested subjects. The oropharyngeal types were not associated with the type of viruses, but were rather linked to the age of the subjects. Moraxella nonliquefaciens exhibited unprecedentedly high abundance in young subjects aged <6 years. The genome of M. nonliquefaciens was found to encode various proteins that may play roles in pathogenesis.ConclusionsThis study identified 6 oropharyngeal microbiome types. No virus-specific bacterial profile was discovered, but comparative analysis of healthy adults and patients identified a bacterium specific to young patients, M. nonliquefaciens.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-014-0583-3) contains supplementary material, which is available to authorized users.
Highlights
Infection by pathogenic viruses results in rapid epithelial damage and significantly impacts on the condition of the upper respiratory tract, the effects of viral infection may induce changes in microbiota
Microbiota of healthy adults The genus Streptococcus was identified as the core microbiome of the healthy human respiratory tract
In all healthy subjects tested in this study, members of Streptococcus dominated the bacterial community, exhibiting an average abundance ratio of 55.8% (Table 1)
Summary
Infection by pathogenic viruses results in rapid epithelial damage and significantly impacts on the condition of the upper respiratory tract, the effects of viral infection may induce changes in microbiota. We aimed to define the healthy microbiota and the viral pathogen-affected microbiota in the upper respiratory tract. Studies to date have revealed that the respiratory tract harbors a homogenous microbiota that decreases in biomass from the upper to the lower tract [5], and that the lung microbiome resembles the oral microbiome, the available evidence is not sufficiently strong, microbiome types are speculated to eventually affect a person’s risk of disease or response to distinct drugs [9]. To reveal the links that exist between microbiome types and clinical traits, we have to first understand the diversity of the microbial community in target body sites
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