Registry to Monitor the Susceptibility to Aztreonam of Pseudomonas Aeruginosa Isolates From Cystic Fibrosis Patients

Key Inclusion Criteria: Subjects must meet all of the following inclusion criteria to be eligible for participation in this study. * Current participant or willingness to participate in the CFF patient registry database * ≥ 6 years of age * Subject has CF as diagnosed by one of the following * Documented sweat chloride ≥ 60 mEq/L by quantitative pilocarpine iontophoresis test, or * Two well-characterized genetic mutations in the CFTR gene, or * Abnormal nasal potential difference (NPD) AND accompanying clinical characteristics consistent with CF. For subjects who lack documentation of either a positive sweat chloride test or an abnormal NPD, and who have only one well-characterized genetic mutation of the CFTR gene, the diagnosis of CF is determined by the Investigator. * FEV1 ≥ 25% predicted and ≤ 90% predicted. * ≥ 2 lower respiratory tract cultures positive for PA with results documented in the subject's medical history. * Subject must be able to provide written informed consent/assent prior to any study related procedure; parent/guardian must be able to give written informed consent as necessary prior to any study related procedure. Key Exclusion Criteria: Subjects who meet the following exclusion criterion are not to be enrolled in this study. • Any serious active medical or psychiatric illness that, in the opinion of the Investigator, would interfere with subject assessment. Note: Other protocol defined Inclusion/Exclusion criteria may apply.