Figure 4

The relative abundance of bacterial OTUs in sputum. The axes are the same as in Fig. 3, but here we compare the extent to which the relative abundance of individual OTUs varies in this data-set. Each dot is a unique bacterial OTU. Certain OTUs, from genera known to cause pneumonia, have been labelled by the genus to which they belong (see key below). The position of each OTU on the plot gives an indication of how its relative abundance in samples varies. Those which are close to the origin, where the dashed-lines intersect, have a similar relative abundance in all samples (zero variance). Those which are far away from the origin are much more abundant in some samples than others. OTUs which are distant from one another, for example Haemophilus_617 and Prevotella_956, have a reciprocal pattern of relative abundance such that when one is high the other is low. OTUs which are close e.g. Pseudomonas_3976, Moraxella_2510 and Klebsiella_1954 all tend to have a higher relative abundance in the same sample. Key: Fuso = Fusobacterium_1252. Prev = Prevotella_956. Veil = Veillonella_1328. Gran = Granulicatella_740. Neis = Neisseria_4683. Acti = Actinomyces_3641. Pseu = Pseudomonas_3976. Mora = Moraxella_2510. Kleb = Klebsiella_1954. Lact = Lactobacillus_2480. Haem = Haemophilus_617. Str_1 = Streptococcus_4318. Str_2 = Streptococcus_1024. Str_3 = Streptococcus_360.