Individuals with cystic fibrosis frequently acquire respiratory infections caused by Pseudomonas aeruginosa bacteria. Although immediate treatment with antibiotics can often clear the infection, in many cases the bacteria adapt to establish permanent colonies in the lungs. These colonies, or biofilms, resist antibiotic treatments and cause significant damage to the airways. Even powerful intravenous antibiotics can only nibble away at the outer edges of the colonies.
Now the results of a new study, published in The Journal of Clinical Investigation, suggest a novel tactic may be able to attack the bacteria at the very center of the biofilms. The research, supported by the CF Foundation, is being conducted by scientists at three sites-University of Washington (UW), University of Iowa, and University of Cincinnati-where there are experts in different aspects of the problem. Led by Pradeep Singh, M.D. at UW, the researchers are using the FDA-approved drug, gallium, to attack P. aeruginosa. Gallium is a metallic element similar to iron.
The study has shown that when P. aeruginosa biofilms were exposed to gallium in the laboratory, the bacteria mistook it for the iron needed for growth and infection, and absorbed it into the very heart of the colony. There, the gallium set to work killing the bacterial biofilm from the inside. Even strains of P. aeruginosa that were resistant to multiple antibiotics were killed by this method. Studies in mice showed that chronic P. aeruginosa infections could also be blocked by gallium treatment.
Because there are several different pathways gallium can take to enter the bacterial cell, researchers think that it could be more difficult for the germs to develop a resistance to the drug. More research needs to be done to identify the level of gallium that is safe and effective for treatment, but this initial study shows it could become another way to attack the bacteria that cause so much destruction to the lungs of people with CF.