Sputum penetration of fusidic acid in patients with cystic fibrosis.

Abstract

We report the sputum penetration and efficacy of fusidic acid in 16 children with cystic fibrosis (CF) who were hospitalized because of acute respiratory tract infection due to Staphylococcus aureus. Penetration into sputum and response to therapy were evaluated after intravenous and oral drug administration. Oral fusidic acid therapy (approximately 1,000 mg/m2/day) achieved highly satisfactory serum (10–50 μg/ml) and sputum (0.6–4.0 μg/ml) concentrations which were several fold greater than the MIC of the infecting S. aureus strains. The average percentage penetration into sputum during the steady state phase of the concentration-time curve was between 5 and 10%. The efficacy of treatment is reflected by improvement in clinical findings and laboratory data. Eradication of S. aureus from the sputum was documented in 14 of the 16 patients, although 6 months later this was shown to be transient in half of them (7 of 14 patients). No staphylococci resistant to fusidic acid were found. Nine of the 14 children with documented staphylococcal eradication from the sputum had received gentamicin in addition to fusidic acid therapy which could have added antistaphylococcal efficacy. Further investigations are needed to formulate the definitive role of fusidic acid in the antistaphylococcal therapy of patients with CF.