Comparison of Composition and Diversity of Bacterial Microbiome in Human Upper and Lower Respiratory Tract

INTRODUCTION Microbiome residing in the airways and parenchymal tissues, as a biological barrier of respiratory tract, plays an important role in maintaining the normal functions of individual＇s respiratory system and preventing the invasion and colonization of exogenous pathogens.H1 Changes of microbial community may result in the occurrence and progression of infectious pneumonia and acute exacerbation of chronic diseases, through disordering commensal microorganisms and increasing invasive ability of pathogens.F21 Traditional methods for detecting bacteria normally rely on culture technique, which have a number of critical problems, including time-consuming and relatively low positive rate of detection. In the last 1 0 years, 16S rRNA gene sequencing technique has been thought to be more comprehensive and reliable than those of culture-dependent methods for monitoring bacterial microbiome in skin, organs, and tracts quantitatively and qualitatively.E31 In this case, choosing credible samples are critical to evaluate the community composition of microbiome in the host tracts, including respiratory tract. In the present study, we aimed to compare the composition and diversity of bacterial community structure in different samples collected from the individuals＇ airways using 16S rRNA gene sequencing technique.