A number of treatments for cystic fibrosis have evolved over the past four decades, based on the experience of clinicians involved in the care of these patients. Some of these treatments were developed without the benefit of large randomised controlled trials which would have been difficult to perform at the time. The value of prophylactic antibiotic treatment againstStaphylococcus aureus in the management of infants and children is an example of a logical practice which has developed on the basis of experience, but which requires careful review as to its efficacy and potential deleterious effects.

Pulmonary infection with S aureus is a frequent problem in patients with cystic fibrosis, particularly during the first decade of life.1 Cross sectional studies show that in this age group, 25−30% of patients cultureS aureus from sputum.2 This may be an underestimate as cough swabs in children unable to expectorate are often negative and infection may only be detected by bronchoalveolar lavage in such circumstances.3 Infection with S aureus is usually associated with symptoms, but asymptomatic carriage is also common.

The approach to the treatment of patients with cystic fibrosis withS aureus infection of the airways …