THE life-saving benefits of soap were first recognised by Ignaz Semmelweis, a Hungarian physician. He discovered in 1847 that hand-washing by obstetricians and midwives could prevent puerperal fever, an infection following childbirth that killed up to a third of women in European hospitals in the mid-19th century.
Semmelweis became known as the saviour of women, but more than a century and a half later, surveys showed one-in-four doctors and nurses in Britain still did not wash their hands consistently between patients.
That abysmal record has been dramatically improved by the CleanYourHands campaign, launched in England and Wales in 2004. It has instilled into medical staff, patients and visitors the importance of washing hands to prevent the spread of superbugs including MRSA and Clostridium difficile.
It was the first such campaign in the world to be rolled out nationally, and the results from the first study of its effects were published online in the British Medical Journal this month.
They show that over the four-year period to mid-2008, orders for soap and alcohol-based hand rub almost tripled, while infections with MRSA and C. difficile almost halved.
There were 1000 deaths from MRSA and 4000 deaths from C. difficile annually in the mid-2000s.
A halving of the infection rate implies a saving of 2500 lives a year.
Researchers from University College London Medical School and the Health Protection Agency say the strong and independent associations between the rise in soap orders and the fall in infection rates remained after taking account of all other interventions. Sheldon Paul Stone, senior lecturer at UCL Medical School, who led the study, said: "Without a doubt, lives were saved by the campaign.
"I would say 10,000 lives over the four-year period of the study was a reasonable estimate.
"If hand hygiene were a new drug, pharmaceutical companies would be out selling it for all they were worth." But Dr Stone warned the gains could be lost after the CleanYourHands campaign ended in 2010.
"It is obvious the campaign should be continued," he said.
"Independent groups have suggested it should. It needs a new focus on staff who use gloves.
"They deal with the most infectious patients but they are much less likely to use soap."
Asked why it had taken more than 150 years to get the message through to doctors and nurses, who already had the professional knowledge about the risks of hand contamination and transmission of bacteria, he said: "As Fawlty Towers once said, it's stating the bleeding obvious. But sometimes the obvious needs stating. The problem is, it doesn't sound very sexy compared with hi-tech medical innovations."
Louise Teare, consultant microbiologist and chair of the Independent Alliance of Patients and Healthcare Workers for Hand Hygiene, said: "The CleanYourHands campaign was unbelievably successful. It is extraordinary that it has taken 150 years to get the message across.
"But throughout history that is, sadly, what happens. Our challenge now is how to make it sustainable."
The campaign was accompanied by posters and regular audits, and was backed by the Health Act (2006), which imposed a legal duty on NHS trusts to provide "hand-washing facilities and hand rubs".
It was reinforced by visits by Department of Health inspectors.
Key to its success was the high- profile political drive to cut infection rates. In the mid-2000s, the Blair government recognised that something had to be done about soaring hospital infection rates which had become a touchstone for the failings of the NHS.
Scandals at Stoke Mandeville hospital and Maidstone and Tunbridge Wells trust, where hundreds of patients died, fuelled public alarm. Patients understood that medical treatment carried a risk but were not prepared to accept that hospitals themselves could pose an even bigger one, by spreading infections.
Doctors had regarded their main task as treating patients, and had seen hospital infections as an unfortunate but inevitable complication of medical care.
That resulted in a fatalistic attitude to the occurrence of infections and an over-reliance on antibiotics to deal with them.
Cases of MRSA grew from less than 100 a year in the early 1990s to 6378 cases in 2006-07 when the infection was linked with more than 1000 deaths. The number of MRSA infections has since fallen to 1114 in 2011-12.
C. difficile cases grew from a few hundred in the early 1990s to 55,681 in 2006-07 and caused about 4000 deaths. They have fallen to 18,005 cases in 2011-12.
According to the Organisation for Economic Co-operation and Development, hospital-acquired infections accounted for more days spent in hospitals in Europe than all other causes of infectious disease - flu, pneumonia, tuberculosis, Aids - combined.
In the case of MRSA, more powerful antibiotics have been required to shift the bug. In the case of C. difficile, antibiotics are themselves a key cause of the infection. They knock out "healthy" bacteria in the gut, allowing the C. difficile bacteria, which are normally held in check, to gain the upper hand.