COLUMBUS, Ohio The bacteria responsible for chronic infections in cystic fibrosis patients use one of the sugars on the germs' surface to start building a structure that helps the microbes resist efforts to kill them, new research shows.
Scientists have determined that the bacterial cell-surface sugar, a polysaccharide called Psl, is anchored on the surface of the bacterium as a helix, providing a structure that encourages cell-to-cell interaction. When multiple bacterial cells join together with the help of such a structure, they form what is called a biofilm, a persistent community of bugs that is able to resist the effects of a human immune response, as well as antibiotic drugs.
In the case of the bacterium being studied, Pseudomonas aeruginosa, the results of biofilm development can be lethal. Chronic infection with these bacteria is what causes the death of most patients with cystic fibrosis, a genetic disease characterized in part by excess mucus in the lungs a condition that can foster creation of the biofilm. Some critically ill hospitalized patients also are susceptible to infection by Pseudomonas, which can lead to sepsis or bacteremia, common causes of death in very sick intensive-care patients.
With Psl clearly identified as the foundation of the matrix, or the architectural glue that holds a biofilm together, scientists hope the research could lead to therapies that target the sugar and thus prevent the development of these masses of bacterial cells.
"From a clinical perspective, if we can figure out ways to inhibit or destroy Psl, we could free up these organisms and they'd be much more readily killed by antibiotics or by the host's defense," said Daniel Wozniak, professor of internal medicine and microbiology at Ohio State University and senior author of the study.
"Many antibiotics target actively growing cells, but biofilms go into a dormant mode of growth. This comes into play with resistance.
|Contact: Daniel Wozniak|
Ohio State University