The machine sits in the corner of the ward

Consultants at Wythenshawe Hospital found that using a vaporiser to spray essential oils into the atmosphere killed off micro-organisms.

Airborne bacterial counts dropped by 90% and infections were reduced in a nine-month trial at the burns unit.

The recipe of oils used in the machine was refined by microbiologists at Manchester Metropolitan University.

Scent Technologies, the Wigan-based company which makes the machine, developed the device to mask smells on wards but found it had a beneficial effect on infections.

The study was started after the recipe of oils was modified by the university team, in conjunction with Wythenshawe consultant Ken Dunn.

It has to be in conjunction with everything else - it can't just be a machine on a ward

Bev Hurst, MRSA campaigner

"Many people will be aware that there are decades of experience with the use of essential oils to control infection," said Mr Dunn.

"I think the novelty of this is putting the two researched technologies together and being able to affect a really surprisingly large area of the ward with a single machine."

There were no MRSA infections in the burns unit while the machine was being used with the recipe of oils.

In the final two months the natural essence blend was removed from the machines and MRSA levels in the air increased - and there was an MRSA outbreak in the ward.

More tests

But despite the apparent success of the trial, MRSA campaigners have urged healthcare professionals to continue with strict cleaning regimes.

Bev Hurst, whose mother Margaret died from an MRSA infection, said: "If this is something that is going to help then that's brilliant.

"But it has to be in conjunction with everything else - it can't just be a machine on a ward."

The National Audit Office estimates hospital-acquired infections contribute to some 5,000 deaths annually.

Further tests are now being carried out.