Pseudomonas aeruginosa in the Cystic Fibrosis Lung

Cystic fibrosis is a common genetically inherited, multisystem disorder caused by loss of function of the cystic fibrosis transmembrane conductance regulator (CFTR) protein, an apically situated anion channel. In the lung, lack of CFTR leads to airway surface dehydration, mucociliary clearance failure and an acidic pH in which innate defence molecules are rendered ineffective. Infection occurs early in life, with P. aeruginosa dominating by adolescence. The characteristic features of the CF airway highlighted above encourage persistence of infection, but P. aeruginosa also possess an array of mechanisms with which they attack host defences and render themselves protected from antimicrobials. Early eradication is usually successful, but this is usually transient. Chronic infection is manifest by biofilm formation which is resistant to treatment. Outcomes for people with CF have improved greatly in the last few decades, but particularly so with the recent advent of small molecule CFTR modulators. However, despite impressive efficacy on lung function and exacerbation frequency, most people with chronic infection remain with their pathogens. There is an active pipeline of new treatments including anti-biofilm and anti-quorum sensing molecules and non-drug approaches such as bacteriophage. Studies are reviewed and challenges for future drug development considered.