Mucoid Pseudomonas aeruginosa alter sputum viscoelastic properties in patients with non-cystic fibrosis bronchiectasis

Pseudomonas aeruginosa (PA) is one of the most common bacteria detected in bronchiectasis (BE) but how mucoid (mPA) and non-mucoid (non-mPA) phenotypes could affect viscoelastic properties is unknown. The aim of this study was to determine the relationship between PA(mPA or non-mPA) isolation, the viscoelastic properties of sputum, chronic colonization and clinical outcomes in patients with BE. <b>Methods:</b> A cross-sectional study was conducted of sputum samples obtained by spontaneous expectoration and sent for microbiology and rheology analysis. Sonication and Sputolysin-Dithiothreitol were used to isolate slow-growing PA. Elasticity and viscosity were measured at two oscillatory frequencies(1 and 100 rad/s). Sociodemographic and clinical data were recorded <b>Results:</b> We analyzed 17 with mPA, 14 with non-mPA and 17 with no organism reported(NOR). There were no differences in viscoelastic properties between the mPA and non-mPA groups; however, compared with the NOR group, the mPA group showed higher elasticity (median 10.30 vs. 5.70,p=0.023), viscosity (2.40 vs. 1.50,p=0.039), and stiffness (10.70 vs. 6.00,p=0.024) values. Both the non-mPA and NOR groups had fewer hospitalizations during the previous year and fewer affected lobes than the mPA group. Compared with non-chronic colonization(25% of participants), chronic colonization with PA(75%) was associated with greater severity on the BE severity index (81% vs. 36%,p&lt;0.001), greater dyspnea, and poorer lung function <b>Conclusions:</b> The mPA phenotype is associated with increased elasticity, viscosity and stiffness of BE sputum. Viscoelastic properties could be used as a marker of mPA to predict early PA colonization.