790 CEPHALEXIN IN CYSTIC FIBROSIS: A PLACEBO-CONTROLLED STUDY

Abstract

The efficacy of cephalexin monohydrate 50 mg/kg/d was evaluated in a placebo-controlled, double-blind, crossover study of patients with cystic fibrosis. Over a 2 year period, 17 patients with mild-moderate disease were treated for 4 month intervals with either cephalexin or placebo. One patient developed drug-related vulvovaginitis and dropped-out of the study. Although colonization by cephalexin-resistant S. aureus was not observed, 2 patients had an increase in sputum concentration of Ps. aeruginosa during antibiotic therapy. Patients previously colonized with ≥ 106 CFU/ml Ps. aeruginosa of H. influenzae had no alteration in flora. Six of 8 patients colonized with ≥ 106 CFU/ml S. aureus had a decrease in S. aureus concentration to < 104 CFU/ml during treatment with cephalexin. During periods of drug treatment, significantly reduced S. aureus colonization (7% versus 26% of cultures), increased weight gain (1.2 versus 0.2 kg/4 months) and less hospitalizations (2 versus 15) were observed (P < 0.01). There were no differences in pulmonary function tests, chest x-rays, or sputum production during periods of antibiotic or placebo treatment. Cephalexin, when compared to placebo, altered the microbial flora and clinical course of some patients with cystic fibrosis.