Tobramycin in treatment of infections due to Pseudomonas aeruginosa in patients with cystic fibrosis.

The effectiveness and safety of tobramycin against infections due to Pseudomonas aeruginosa in patients with cystic fibrosis were studied in 15 patients with moderate-to-severe exacerbation of chronic pulmonary infection. Seventeen courses of treatment were given. Tobramycin (5-7.5 mg/kg per day) was administered intravenously in three divided doses per day (seven to 21 days). All specimens of sputum yielded moderate-to-heavy growth of P. aeruginosa; all isolates were inhibited by 4 mug of tobramycin/ml, and in seven cases isolates were not inhibited by 4 mug of gentamicin/ml. The mean levels of tobramycin in the blood were 4.4 mug/ml 0.5-1 hr and 0.8 mug/ml 7.5-8 hr after administration. All patients received an antistaphylococcal agent before, during, and after therapy. All patients except for two received 750 mg of carbenicillin/kg per day intravenously in six divided doses and 1 g of carbenicillin in a mask for inhalation three times a day. Both clinical and radiological improvement was noted in all patients. The white blood cell count, which was elevated in seven patients, returned to normal, and levels of blood gases improved. P. aeruginosa was eliminated from the sputum in five cases. No adverse side effects were noted.