Cystic fibrosis (CF), a life-shortening genetic disease, is marked by acute episodes during which symptoms of lung infection increase and lung function decreases. These pulmonary exacerbations are treated with varying antibiotics for varying time periods based on needs determined by individual patients, their families, and the health care providers. Cystic fibrosis pulmonary guidelines for the treatment of pulmonary exacerbation published by the Cystic Fibrosis Foundation (CFF) in 2009 provided recommendations for treatment and also identified key questions for which additional studies were needed.