In this issue we are joined by Dr. Shawn Aaron of University of Ottawa in Ontario, Canada. Dr. Aaron will discuss infection in patients with optimal therapy of chronic Pseudomonas aeruginosa cystic fibrosis, describe the pathophysiology of pulmonary exacerbations associated with Pseudomonas infection in patients with cystic fibrosis, and evaluate the optimal choice of antibiotics to treat Pseudomonas-associated pulmonary exacerbations in patients with cystic fibrosis.