People with cystic fibrosis (CF) often develop chronic pulmonary infections which are caused by a variety of organisms, the most predominant being Pseudomonas aeruginosa. Antibiotics are important in managing CF lung infections. Antibiotic use in CF was altered about ten years ago with the approval of inhaled tobramycin, an aminoglycoside which is effective in treating P. aeruginosa. A decade later, CF clinicians are increasingly concerned about the likelihood of induction of aminoglycoside-resistance with prolonged use of inhaled tobramycin to treat chronic P. aeruginosa airway infections. The goal of this study is to examine the current microbiology and susceptibility of organisms from CF sputum, correlate it with antibiotic use, and compare it with previous data.