Gene warfare against superbugs

Patients recovering in hospital are vulnerable

Superbugs may have a genetic weakness which could lead to more effective drugs to fight them, scientists believe.

However, it will be years before these prospective gene therapies find their way out of the laboratory onto the hospital ward.

The two genes discovered by researchers at Rockefeller University in New York are thought to help bacteria outwit conventional antibiotics.

Over the years, certain strains of bacteria have become harder - or even impossible - to treat effectively with a wide range of previously-useful drugs.

A wound infected with one of these bugs could pose a real danger to a weakened or vulnerable patient.

Hundreds of deaths

The resistant strains are more likely to develop in environments where lots of antibiotics are being used, such as hospitals or nursing homes, because the drugs will weed out the less resistant strains, leaving only the tougher ones to reproduce.

"Superbugs", or resistant bacteria, are wholly or partly responsible for hundreds of extra deaths in hospital each year, and cost the health service millions of pounds.

Many hospitals have introduced strict hygeine policies to try to cut the chance of infection.

Normally, antibiotics like penicillin can breach the bacterial cell wall, killing the bug.

The Rockefeller project found that resistant bacteria are able to rebuild the cell wall, and found that the two genes were key in that process.

They are responsible for the production of natural chemicals called muropeptides which are important to the cell wall structure.

By targeting those two genes, they hope, the bacteria might not be able to repair itself effectively, and its resistance to conventional antibiotics might be stripped away.

Alexander Tomasz, who is leading the research project, has been looking at how some of the most common strains of bacteria behave.

One of them, Staphylococcus aureus, can become highly resistant to conventional antibiotics, and many hospitals have resident strains of so-called methycillin-resistant bugs (MRSA).

'Last line of defence'

A few cases of Staphylococcus resistant even to the "last line of defence", a toxic antibiotic called vancomycin, have been reported worldwide.

Doctors are trying to keep one step ahead of the constantly evolving bacteria by developing new classes of antibiotics.

The latest research is a novel approach, but it is not certain whether it will be safe to use on bacteria actually living in the human body.

Dr Tomasz said: "We have now identified two genes that are responsible for making these branched muropeptides, and we have shown for the first time that by inactivating these genes we can restore penicillin's potency.

"This opens the door to the development of new drugs that would act synergistically with penicillin by blocking the production of the branched peptides."

The research was published in the journal The Proceedings of the National Academy of Sciences.