The main cause of death in people with cystic fibrosis is due to chronic lung infection. People with cystic fibrosis now live longer due to the aggressive use of antibiotics to treat lung infections. Traditionally, antibiotics are chosen based on the results of laboratory testing of each antibiotic separately against the bacterium (or bug) that is found in the lungs of someone with cystic fibrosis. Antibiotics tested in combination may have activity against a bacterium even if ineffective when tested alone. It is unclear, however, if choosing antibiotics to treat lung infections caused by Pseudomonas aeruginosa (P. aeruginosa) in people with cystic fibrosis, based on the results of testing antibiotics in combination is better than choosing antibiotics based on the results of testing antibiotics separately.
The search identified one study that tried to answer this question and was eligible for inclusion in the review. It was a multicentre, randomised, double-blind controlled clinical study. The study looked at whether using the results of testing antibiotics in combination versus testing antibiotics separately improved clinical outcomes in people with CF with lung infections. The study randomised 132 people with cystic fibrosis, the majority of whom had lung infections with P. aeruginosa. The study investigators were able to provide us with the data for those infected only with P. aeruginosa for the time until next lung infection. Choosing antibiotics to treat P. aeruginosa lung infections in people with CF based on results of testing antibiotics in combination did not lead to a longer time until the next lung infection compared to choosing antibiotics based on results of testing antibiotics separately.
The study was limited by the fact that it was not designed to specifically look at people with cystic fibrosis with P. aeruginosa infections. In addition, choosing antibiotics to treat lung infections in cystic fibrosis based on testing antibiotics in combination may be helpful only in those who have already failed antibiotic therapy based on testing antibiotics separately. Future studies addressing these concerns will require international collaboration due to the limited number of people with cystic fibrosis who meet these criteria.