New compounds could make drug-resistant bacteria harmless

Sep 12 2006

Just as the medical world has become concerned over the apparent resistance of some bugs to antibiotics, scientists have made significant progress towards the development of a new generation of antibiotics.

The scientists at the University of Wisconsin-Madison have developed a way to fight deadly infections which rather than killing the bacteria directly, blocks the chemical signals that the bacteria use to communicate, hopefully stopping them spreading.

Bacteria use chemical signals to trigger the majority of human infections and when these signals reach a certain point the bacteria change the way they grow and produce virulence factors that lead to infection.

Chemical signals encourage the bacteria to produce slimy biofilms that protect the bacteria and make them physically resistant to antibiotics.

The scientists have come up with a group of compounds that stop bacteria "talking to each other", which interferes with their ability to spread infection rendering the bacteria benign instead of killing them off.

The scientists believe the compounds, which are small organic molecules, could when combined with powerful antibiotics, knock out deadly infections.

As the compounds do not target bacterial growth, the potential for the development of bacterial resistance is considerably reduced.

In tests the compounds have been seen to actively block the spread of a common bacteria which causes fatal lung infections in people with cystic fibrosis and leads to life-threatening blood infections in patients with serious burns or immune system disorders such as AIDS.

The U.S. National Institutes of Health estimated in 2002 that up to 80% of bacterial infections spread by using biofilms which offer such good protection that in many cases the bacteria could be killed only by giving the patient a lethal dose of antibiotics.

In a collaborative research effort with Fred Ausubel, Ph.D., a molecular biologist at Massachusetts General Hospital in Boston, the researchers used a new technique called microwave-assisted chemistry to design compounds similar to those used by bacteria.

When they come into contact with bacteria they act as "earplugs", in effect leaving the bacteria oblivious to their neighbours and never receiving the signal to attack or produce biofilms.

Dr. Helen Blackwell, the head scientist for the research, says further tests are needed to prove the compounds are capable of preventing diseases in humans.

Dr. Blackwell says the need for new antibacterial therapies is urgent, and the work represents a new therapeutic approach which is clinically timely.

The compounds have not as yet been tested in humans or plants.

The research was presented at the annual meeting of the American Chemical Society, and though in it's early stages, it holds promise for the treatment for some of the the world's most deadly diseases.

The World Health Organisation has recently warned that tuberculosis (TB), which has now infected nearly 15 million people worldwide, has developed in some countries into an extreme drug-resistant strain, and it is spreading across the globe.

The deadly strain of TB has already killed people in several countries.