"We think that the bacteria in a cystic fibrosis sufferer's lungs are partly living in communities called biofilms, and although medical scientists have investigated their strongly antibiotic-resistant properties, very little research has been done to investigate any active contribution the biofilms might have in causing diseases in the first place," says Dr Welch.
A widely-held view is that biofilms serve as reservoirs of bacteria that do relatively little harm; they just sit there. The main danger is thought to be from 'blooms' of free living cells which occasionally break away from the biofilm and cause periods of poor lung function in the cystic fibrosis patients. "In this scenario, it follows that bacteria in a biofilm will produce fewer disease-causing chemicals than free-living cells of the same type of bacteria, which is a prediction that we can test," says Dr Welch. "We found that, in contrast to expectation, biofilms do indeed produce harmful chemicals. However, the type of tissue-degrading enzymes and toxins made by the biofilm bacteria differ from those produced by free-floating bugs, which may help them to survive attacks by our immune systems."
In addition, the scientists discovered that the biofilm bacteria can produce a protein which their analysis suggests is similar to one of the active ingredients in rattlesnake venom. In the case of rattlesnake venom the protein causes the host cells to commit suicide and die, which is one reason why rattlesnake bites are so dangerous. The research team is currently studying the protein to see if it functions in the same way.
In addition the scientists have found evidence that the trigger for the bacteria to start producing these extra virulence fact
|Contact: Lucy Goodchild|
Society for General Microbiology