Experts target toxin in bid to overcome hospital superbugs

Scottish scientists believe they may have found a new way of battling the killer hospital superbug MRSA.

The research suggests that targeting a toxin released by virtually all strains of MRSA – meticillin-resistant Staphylococcus aureus – could help experts develop new drugs that can fight the infection.

Levels of MRSA in Scottish hospitals are now at historically low levels, but the infection, which is resistant to most antibiotics, can still prove fatal in some patients.

The latest research, by the University of Edinburgh, discovered a toxin known as “SElX”, which leads the body’s immune system to go into overdrive and damage healthy cells.

The toxin is made by 95 per cent of Staphylococcus aureus bacteria, including MRSA strains linked with hospital-acquired infections.

When it is released, it triggers an over multiplication of immune cells, which can lead to high fever, toxic shock and potentially fatal lung infections.

Experts believe that the new study, published in the journal PLoS Pathogens, will help research to find drugs that could target SElX and prevent damage to healthy cells.

The Edinburgh researchers worked with US colleagues in Iowa and Mississippi to make the discovery. The researchers looked at a strain of MRSA known as “USA300” which can cause severe infections in otherwise healthy individuals.

MRSA strains are known to produce different types of toxins, but scientists found that SElX is made by virtually all strains of the superbug.

This toxin belongs to a family of toxins known as “superantigens”, which can invoke an extreme immune response. Dr Ross Fitzgerald, from The Roslin Institute at the University of Edinburgh, said: “If we can find ways to target this toxin, we can stop it from triggering an over-reaction of the body’s immune system and prevent severe infections.”

Figures from Health Protection Scotland show cases of MRSA reported in Scotland are now at their lowest levels since surveillance began in 2005. The number of cases of the infection decreased from 69 to 52 – a drop of 25 per cent – between the first and second quarter of this year, according to the statistics.

Compared with the same period last year, cases were down from 79, with a reduction of over 75 per cent compared with the same period in 2007 when 215 cases were reported. Health secretary Nicola Sturgeon welcomed the figures, but admits there is no room for complacency as the NHS also faces continued threats from bugs such as Clostridium difficile and the risk that other infections will develop resistance to antibiotics.

The Scottish Government has invested more than £50 million funding over the past three years to tackle healthcare-associated infections, with measures including better enforcement of hand hygiene in hospitals and more inspections on wards.

The latest research in Edinburgh was funded by the Biotechnology and Biological Sciences Research Council, the National Institutes of Health, USA, the US Department of Agriculture and Pfizer Animal Health.