Ceftazidime monotherapy vs. combined therapy in Pseudomonas pulmonary infections in cystic fibrosis.

To evaluate whether the addition of an aminoglycoside might enhance the clinical efficacy of ceftazidime in cystic fibrosis patients with acute exacerbations of chronic Pseudomonas lung infections we carried out a prospective, comparative, randomized blind study with three schedules: ceftazidime vs. ceftazidime plus sisomicin (C/S) vs. piperacillin plus sisomicin, for a total of 60 courses of 14 days of treatment. Each treatment led to clinical and radiologic improvement with marked reduction of signs of acute infection. Statistically there was no significant difference in clinical responses among the schedules. No side effect appeared during treatments with ceftazidime or C/S. Hyperpyrexia was seen in 35% of patients receiving piperacillin. Decrease in Pseudomonas aeruginosa count to less than 10(5) colony-forming units/ml of sputum was achieved in 60% of patients treated with C/S and in 30% of patients who received ceftazidime or piperacillin plus sisomicin (statistically not significant). A transient increase in mean geometric minimal inhibitory concentrations for ceftazidime and piperacillin was observed at the end of the combined therapies. A larger percentage of persistent resistant strains of P. aeruginosa was seen after the combined therapies. We conclude that ceftazidime as monotherapy may be an effective alternative in Pseudomonas lung infections in cystic fibrosis patients. Its clinical efficacy seems not to be enhanced by the addition of an aminoglycoside, although reduction of Pseudomonas in the sputum was better achieved by the combination of C/S.