Bacterial discovery may help CF patients

Microbiologists from Australian and Danish have discovered a way to prevent or disturb the formation of bacterial colonies, which they believe may bring a string of benefits from preventing lung infections in cystic fibrosis sufferers to cleaner contact lenses. The discovery, by scientists at the University of Queensland's Institute for Molecular Bioscience and the Technical University of Denmark, was released Friday and is published in the journal Science.

Researchers found a DNA-destroying enzyme, called DNaseI, may break up or disrupt the formation of stubborn biofilms of the bacteria Pseudomonas aeruginosa. Biofilms are communities of bacteria enmeshed in a matrix of long, chain-like molecules, which includes DNA. When biofilms form in the human body, as they frequently do in the lungs of people with cystic fibrosis, they are particularly resistant to antibiotics and the body's own immune response.

Cystic fibrosis is a genetic disease characterized by the build up of thick sticky mucus in the lungs and pancreas, leading to breathing difficulties and nutritional problems.Co-author of the paper, Professor John Mattick, said infection by this bacteria resulted in inflammation and tissue damage in the lungs of cystic fibrosis patients.

"During lung infection, Pseudomonas aeruginosa creates a biofilm, a soup rich in proteins, complex sugars and DNA. This biofilm plays a vital role in establishing bacterial colonies that are also resistant to antibiotics and the host's immune response," Mattick said.

Scientists have known for a while the biofilm of this pathogen has a high DNA content but they thought the DNA in the matrix was not an important part of the biofilm structure. The new research found the majority of the matrix material in the biofilm consists of DNA, and that it seems to be released by the living bacteria.

The researchers found treating the biofilm with the DNaseI enzyme, which breaks down DNA into its component molecules, destroys the biofilm and restricts the establishment of infectious colonies. It appears DNaseI treatment may also be beneficial as an early prophylactic measure to prevent the establishment of bacterial infection in the lungs of people with cystic fibrosis.

However, while DNaseI dissolved the biofilm during its early stages of growth, it became less effective over the next 84 hours. The authors propose the matrix in mature biofilms may be strengthened by other substances or that mature biofilms may produce sufficient counter-enzymes to locally inactivate the DNaseI.

Mattick's co-author, Dr. Cynthia Whitchurch, told United Press International her research began several years when she started wondering whether DNA might have a structural role. "It was a fortunate observation," she said. She said while more research is needed, she is hopeful the discovery will be useful in other settings where biofilm form, such as inside catheter tubes and on the surface of contact lenses.Professor Staffan Kjelleberg, a microbiologist who specializes in biofilms at the University of New South Wales, was surprised when he heard of the discovery.

"The discovery that DNA is the major component of the matrix, and the use of DNaseI to dissolve it is a breakthrough," he Kjelleberg told UPI. "My question is, is it also relevant to other biofilms or only those pertaining to Pseudomonas. You see, there are many types of biofilm, and they are formed everywhere there's an aqueous environment. So the possibilities here are endless."