People with cystic fibrosis suffer lung infections due to thick secretions and commonly suffer infections with unusual bacteria, including the bacteria Pseudomonas aeruginosa. These bacteria become resistant to treatment with antibiotics. Long-term infection leads to a poorer quality of life and reduced lung function. There are no new antibiotics currently in development that use a new mode of action. New agents - antibiotic adjuvants are required that can make bacteria more sensitive to either antibiotics or to the immune system, interfering with the formation of bacterial colonies in the lungs.
We identified seven antibiotic adjuvant approaches including sugars, garlic, monoclonal antibodies, chick yolk antibodies, bacteriophages, β-carotene and zinc supplementation. We included three trials of these approaches (β-carotene, garlic and zinc) that met our inclusion criteria. Neither β-carotene or garlic showed a significant improvement in clinical state or the incidence of infection. The study of zinc supplementation found a reduction in the requirement of oral antibiotics, but not of intravenous antibiotics. It is difficult to explain this discrepancy and so the significance of the effect of zinc remains uncertain. This study published selected results, however the authors have kindly provided additional data.
We were unable to identify an antibiotic adjuvant therapy that had a significant beneficial effect on either lung function, rate of infection or quality of life. Further randomised controlled trials are required before routine use of any of these therapies can be recommended.