Treatment with macrolide antibiotics for people with cystic fibrosis and chronic chest infection

People with cystic fibrosis suffer from chest infections, often caused by the bacteria Pseudomonas aeruginosa. This bacteria is resistant to nearly all antibiotics that can be taken by mouth. Macrolide antibiotics, e.g. azithromycin, have no direct killing effect on Pseudomonas aeruginosa, but they may reduce the activity of these bacteria. We have included ten randomised controlled trials with a total of 959 participants in this review. Eight of these trials compared azithromycin (a macrolide antibiotic) to placebo and two compared different doses of azithromycin. Four trials in children and adults (549 participants) showed significant improvements in lung function after treatment with azithromycin compared to placebo at six months; although data from later time points are not so clear. Patients treated with azithromycin were about twice as likely to be free of pulmonary exacerbation; needed fewer oral antibiotics and had fewer instances of Staphylococcus aureus in cultures from their lungs and airways. Adverse events were not common and not obviously associated with azithromycin, although there was an increase in resistance to macrolides. Most studies used a three times a week dosing schedule. Taking a high weekly dose was linked to an increase in mild gastrointestinal adverse events. Further multicentre studies are needed to look at the long-term effects of this antibiotic treatment, especially for infants diagnosed through newborn screening.