Azlocillin in cystic fibrosis.

The combination of azlocillin and gentamicin or tobramycin, in the treatment of lower respiratory tract infection due to Pseudomonas aeruginosa in patients with cystic fibrosis, was evaluated. Twenty patients, 10 boys and 10 girls (mean age 13 1/2 years) who had lower respiratory tract infection with positive sputum culture for P. aeruginosa, were given azlocillin i.v. 20 mg/kg every 8 hours for 10 to 12 days. In addition, either gentamicin, 2.5 to 4 mg/kg i.v. every 12 hours, or tobramycin, 4 to 5 mg/kg i.v. every 8 hours, was given. The antibiotics were given in short-term infusions (20 minutes). Besides the antibiotic treatment, the patients received inhalation therapy, pulmonary physiotherapy, and pancreatic enzymes. Pharmacokinetic studies showed that azlocillin concentrations in serum were within therapeutic levels, and in sputum they inhibited 75% of all P. aeruginosa strains. However, in only 12 of the 52 treatment courses was Pseudomonas eliminated from the sputum.