Page last updated at 23:43 GMT, Sunday, 7 September 2008 00:43 UK

Venomous clues in lung bug battle

Pseudomonas aeruginosa
Pseudomonas aeruginosa forms biofilms in the lungs

Bacterial colonies in the lungs of cystic fibrosis patients use chemicals found in snake venom to attack them, say UK researchers.

The Pseudomonas bug lives in "biofilm" communities in the lungs, becoming resistant to antibiotics and increasingly hard to treat.

A University of Cambridge team identified several harmful "virulence factors" it produces in this state.

Targeting these could help develop new drugs to tackle superbugs, they said.

The acid test is what happens in the human.
Professor Ian Chopra
Leeds University

When bacteria grow in the body, they can either live as individuals or join forces to form "biofilms", which appear to be able to remain in a semi-dormant state and cause long-lasting problems.

These can be highly difficult for doctors to treat, particularly in cystic fibrosis patients, where long-term Pseudonomas infection, thriving in the thick mucus produced in the lung, is usually the reason for early death.

The Cambridge University research, presented at the Society for General Microbiology Conference in Dublin, suggests that these reservoirs of bacteria are more active than previously thought.

Tests in the laboratory suggest they are constantly attacking the body by producing tissue-destroying enzymes and poisons.

One of those spotted by the researchers is chemically similar to rattlesnake venom, which, in the far higher doses delivered by the snake, can cause catastrophic tissue damage.

Toxin trigger

Dr Martin Welch, who led the project, said: "This is the first time that anyone has successfully proved that the way the bacteria grow affects the type of proteins they can secrete and therefore how dangerous they can potentially be to our health.

"We found that, in contrast to expectations, biofilms do indeed produce harmful chemicals."

The team found evidence that the "trigger" for the release of these harmful toxins was turned out shortly after the biofilm started to form. They hope a drug can be found to target the poisons.

This would have a potential application not just in cystic fibrosis, they said, but also in the treatment of hospital superbugs.

Professor Ian Chopra, a biofilm specialist from Leeds University, said anyone looking to turn laboratory research into a viable treatment for the cystic fibrosis lung had several obstacles to overcome.

He said: "It's very interesting work but we are still not sure whether any model of the cystic fibrosis biofilm in the laboratory is a good match for the actual lung.

"If it is hard for an antibiotic with small molecules to be taken up by a biofilm, then it may be just as hard for an antibody to do it.

"The acid test is what happens in the human."


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