Flagellar motility and the mucus environment influence aggregation-mediated antibiotic tolerance of <i>Pseudomonas aeruginosa</i> in chronic lung infection

Antibiotic treatment failure of <i>Pseudomonas aeruginosa</i> infection is a key driver of mortality in muco-obstructive airway diseases (MADs). The bacterial mechanisms that contribute to antibiotic tolerance in MADS infection are poorly understood. We investigated the impact of swimming motility behaviors on <i>P. aeruginosa</i> antibiotic tolerance in the context of the diseased mucus environment. Loss of flagellar motility, a common adaptation in chronic lung infection, drives antibiotic tolerance by promoting aggregate formation under physiologically relevant mucin concentrations. We uncovered novel roles of the flagellar stators in motility and mucus aggregate formation. Furthermore, neutrophil elastase, an abundant host-derived antimicrobial protease, promotes antibiotic tolerance and aggregation by impairing flagellar motility. These results further our understanding of the formation of antibiotic-tolerant aggregates within the MADs airway, revealing potential new targets to improve antibiotic treatment of chronic <i>P. aeruginosa</i> airway infection.