Study for Evaluating the Real Use of Inhaled Aztreonam Lysine in Patients With Cystic Fibrosis

Inclusion Criteria: * Patients above 6 years old that have been treated with Aztreonam Lysine (AZLI) at any time within 12 months before starting the treatment * Diagnosis of Cystic Fibrosis confirmed * Chronic infection by Pseudomonas aeruginosa * Patients can be treated with any inhaled antibiotic before or after AZLI treatment * Patients have to have the following FEV1 measures: 12 months before starting AZLI; at AZLI initiation; 12 months after starting AZLI * For lung transplant patiens, only data before the transplant will be collected. Exclusion Criteria: * Non applicable