Figure 1.

(a) Number of bacteria per sample among the respiratory tract. We found significantly lower amount of bacterial cells in samples from the lower airways (bronchoalveolar lavage, BAL) and human lung tissue (HLT) compared to the upper airways (oral swabs, OS). There was also a significant difference between BAL and HLT. (b) Shannon’s diversity index was numerically lower in the upper airways. (c) The distribution of the five most abundant phyla in the airways and the lung tissue. The mean relative abundance of Bacteroidetes in the airways was significantly larger than in the lung tissue, while Actinobacteria showed a significantly higher relative abundance in the lung tissue. (d) Looking at the distribution of the most abundant genera, Prevotella, Veillonella and Streptococcus occurred with a significantly higher mean relative abundance in the upper and lower airways than in the lung tissue. In contrast, Pseudomonas and Propionibacteria were significantly more abundant in HLT (Outlier are marked with a black dot).