BRITISH scientists have identified a genetic “Achilles heel” in the superbug MRSA that could lead to new ways of fighting the infection.

By closely studying MRSA genes, the team found possible new roles for 22 that help the bacterium cause disease.

One gene, known as ftsH, was singled out as a vulnerable weak spot that could be the target of new drug development.

MRSA, methicillin resistant Staphylococcus aureus, is a mutant form of a common microbe which is immune to most antibiotics.

In 2009 there were an estimated 781 deaths in the UK involving MRSA. The majority of MRSA infections occur in hospital as a result of the bug entering wounds.

The research team, including scientists at the Medical Research Council Human Genetics Unit in Edinburgh and the Universities of St Andrews, Dundee and London, produced a “gene map” to improve their understanding of how MRSA develops resistance.

For the first time, they were able to unravel relationships between 95% of MRSA genes.

They also examined an antimicrobial agent called Ranalexin, derived from the skin of a bullfrog, which is able to kill MRSA.

Computer analysis, coupled with laboratory tests, showed that the drug works by weakening the bacterial cell wall and membrane.

Dr Ian Overton, from the MRC Human Genetics Unit, said: “Multidrug resistant Staphylococcal infections such as MRSA are a worldwide problem and strains resistant to existing treatments continue to emerge.

“The development of new drugs is therefore important. Our network biology approach has given insights into how Ranalexin works to kill MRSA and helped us to understand more about how infections may develop. This knowledge contributes towards new strategies for treating MRSA.”