Aztreonam for Inhalation Solution (AZLI) for the Treatment of Exacerbations of Cystic Fibrosis. An Randomised, Crossover Pilot Study of AZLI Plus Intravenous Colistin® Versus Standard Dual Intravenous Therapy

AZLI, marketed as Cayston, is an inhaled beta-lactam antibiotic. It has a license for the chronic suppression of Pseudomonas aeruginosa (PA). Current standard practice dictates the use of two IV antipseudomonal antibiotics for the treatment of acute pulmonary exacerbations. The increasing survival, and hence population, in CF means that newer antimicrobial strategies are required in order to manage antimicrobial resistance, minimise adverse systemic effects of heavy antimicrobial exposure and also make effective use of resources. Inhaled antibiotics are commonly used in the chronic suppression of PA yet their use has not been thoroughly investigated in acute pulmonary exacerbation. Inhaled antibiotics deliver their drugs directly to the target-site with minimal systemic absorbance, making them an attractive candidate for treatment of acute exacerbations.

Recently, it has become apparent that the bacterial community is much more complex than initially thought. The microbiome, a term used to describe the polymicrobial community in the lungs, has become apparent due to the use of modern culture-independent methods to detect bacteria. The microbiome changes in composition and structure around the time of exacerbations and in response to treatment, although these changes have not been prospectively characterised.

We have designed an open-label randomised, controlled cross-over trial to investigate the clinical effectiveness of of AZLI in the treatment of acute pulmonary exacerbation, whilst simultaneously comparing the effect inhaled and intravenous antibiotics have on the microbiome.