• Cystic Fibrosis
• Respiratory Infection

Treatment of infection in cystic fibrosis (CF) lung disease should be based on identifying which organisms warrant treatment, requiring evidence that the pathogen leads to worse outcomes and that intervention yields better clinical outcomes. This has been demonstrated for Pseudomonas aeruginosa, where eradication of early infection and suppression of chronic infection have become the standard of care. This approach has not been broadly adopted for Staphylococcus aureus, in part because of insufficient evidence demonstrating an association with worse outcomes and treatment has not proven better outcomes. However, there is a rising concern about methicillin-resistant S. aureus (MRSA). MRSA infection in patients with CF has been associated with more severe pulmonary disease and poorer clinical outcomes.1–3

Rates of MRSA infection have increased dramatically and now exceed 25% of the CF population in the USA, paralleling rates in the general community.4 Notably, prevalence rates of MRSA are significantly lower in other countries including the UK and Australia (each 2.6%).5 ,6 Given these observations, efforts to treat MRSA would seem relevant, but evidence of treatment benefit is lacking. Until now, treatment approaches for MRSA have been anecdotal and decision-making has been supported by small studies.7–15

The results of a prospective, open-label randomised study of the treatment of early MRSA infection in patients with CF are reported.16 The primary endpoint was a microbiological one—could they render the patient culture negative, often assumed to represent eradication? Participants were randomly allocated to treatment or a period of observation. Treatment included antibiotics for 14 days in addition to hygienic measures aimed to reduce nasal, cutaneous and domestic environmental colonisation. The key findings of the study were a higher proportion of patients without MRSA in airway cultures at 28 days (82%—treatment arm vs 26%—observation arm).

Two important trial conduct issues were identified …