635. Genomic Evolution and Progression of Antimicrobial Resistance in a Series of Extensively Drug-Resistant Pseudomonas aeruginosa (XDR-Pa) Isolates from a Cystic Fibrosis Lung Transplant Recipient

Background Chronic respiratory infection due to extensively drug-resistant Pseudomonas aeruginosa (XDR-Pa) is a significant cause of mortality in cystic fibrosis (CF) patients. The CF respiratory anatomy, chronic antibiotic use, and PA colonization creates a milieu for high evolutionary pressure and genetic diversity. We sought to explore the progression of antibiotic resistance and genome evolution of XDR-Pa in a longitudinal series of isolates collected from an18-year-old CF patient who underwent lung transplantation.