Figure 4

Biplot using the first two PLS-DA factors. The plot shows a good separation of P. aeruginosa positive chronic colonized patients (triangles and squares) and P. aeruginosa negative patients (circles). Significant correlation of volatiles is suggested when volatiles project between r=0.75 (inner circle) and r=1 (outer circle). The vector shows the direction where volatiles are positively correlated with chronic P. aeruginosa. The pattern of volatiles could explain P. aeruginosa infection in 86% using the first two PLS-DA factors (62% and 24%). X and Y axis both show partial least square regression r. Each PLS factor explains 10% and 6% of the X-variation respectively. The light gray symbols visualize the volatile organic compounds, sorted by structure. Squares: Chronic colonization and positive sputum cultures for P. aeruginosa at the time of study. Triangles: Chronic colonization but negative sputum culture for P. aeruginosa at the time of study. Circles: Negative for P. aeruginosa.