Efficacy and Safety of 28 or 56 Day Treatment for Pseudomonas Aeruginosa in Children With Cystic Fibrosis

Inclusion criteria: * Male or female patients ≥ 6 months old * Diagnosis of cystic fibrosis (CF) based upon the following historical criteria performed prior to study participation: 1. confirmed sweat chloride \> 60 mEq/L by quantitative pilocarpine iontophoresis (at least 2 tests), OR 2. genotype with two identifiable mutations consistent with CF. * First or early lower respiratory tract infection with Pseudomonas (P.) aeruginosa documented by either of the following: 1. first infection defined by the first P. aeruginosa isolated from sputum or deep throat cough swab culture, OR 2. P. aeruginosa from sputum or deep throat cough swab culture following at least 1 year of negative cultures (documented with at least 4 negative cultures during this year and no positive cultures) and no anti-pseudomonal treatment during this 1-year period, OR 3. P. aeruginosa from sputum or deep throat cough swab culture following at least 2 years of negative cultures (documented with at least 2 negative cultures per year and no positive cultures) and no anti-pseudomonal treatment during this 2-year period. * Written informed consent by the patient and/or parent/legal guardian according to local country regulations. Exclusion criteria: * History of aminoglycoside hypersensitivity or adverse reaction to inhaled aminoglycoside. * Signs and symptoms of acute pulmonary disease, eg, pneumonia, pneumothorax. * Administration of any investigational drug within 30 days prior to enrollment. * Administration of loop diuretics within 7 days prior to study drug administration. * Personal/family history of abnormal hearing, other than typical hearing loss associated with the aging process. * Abnormal result from an audiology testing (defined as either a unilateral pure-tone audiometry test showing a threshold elevation \> 20 decibels \[dB\] at any frequency across the frequency range 0.25-8 kHz or the absence of emission at the evoked otoacoustic emission test). * Positive urine pregnancy test at Day 1 (Baseline) for all female patients who have reached menarche. * Use of macrolide antibiotics as a maintenance therapy for 12 or more days during the 28 days prior to Baseline. * Antibody titers ≥ 1000 for any of the 3 P. aeruginosa exoenzymes: Exotoxin A, alkaline protease, or elastase (status to be determined between Baseline and Day 28).