The NHS trust that controls Stoke Mandeville Hospital was given the lowest possible rating for infection-control standards in a recent set of NHS performance indicators.

The NHS trust that controls Stoke Mandeville Hospital was given the lowest possible rating for infection-control standards in a recent set of NHS performance indicators.

The Healthcare Commission said the trust's record on preventing the spread of bugs such as Clostridium difficile was "poor" and significantly below what was expected.

Despite having a world-famous reputation for its spinal unit at Stoke Mandeville, the Buckingham-shire Hospitals NHS Trust was awarded just one star in last year's performance ratings by the Healthcare Commission.

The ratings give NHS trusts between zero and three stars, based on a series of indicators such as infection control, waiting times and death rates.

Infection control is assessed on compliance with national standards and levels of controlling bugs picked up while patients are in hospital. The Buckinghamshire Hospitals Trust was only given a "one" rating for infection control, the lowest possible mark.

Only 17 other acute NHS trusts out of 177 were given a similar score, with the majority being rated as acceptable or good. The trust was also told it was "significantly underachieving" in terms of financial management, a further reason for its one-star status.

In its plan for 2005, the trust says that a key aim this year is to achieve two stars in the performance ratings. A spokesman said the trust had broken even last year and was addressing the issues raised in the performance indicators.

But the rating does not reflect well on the world-famous hospital, whose incidents of C. difficile - which produces hardy spores that are resistant to some methods of cleaning - have raised fresh concerns about deteriorating cleanliness.

The public service union Unison fuelled those fears when it warned yesterday that hospital cleaners were being told to clean as many as four wards in an hour by private companies eager to cut costs and raise profits.

Chronic shortages of cleaners and a high turnover of poorly paid staff were adding to the problem of hospital infections, a report by the union said.

The number of full-time cleaning staff has fallen by 45 per cent in the 20 years since services were "contracted out" of the NHS to private companies. In 1986, there were 67,000 full time cleaners in the health service - now there are just 36,000, the report found.

Dave Prentis, general secretary of Unison, said: "Dirt isn't cheap and the human cost is enormous. The Government and hospital managers should listen to hospital cleaners when they say what's needed is more staff, better equipment, proper training, effective teamwork and greater involvement in decision-making. Unison would like to see hospital cleaning brought back in-house and under the direct control of staff on the wards."

The cleaning contract at Stoke Mandeville was held jointly by two private companies, but next year the hospital plans to second members of staff under a new type of contract to another company which would allow it to retain responsibility for the staff and for standards of hygiene.

The revelations about Stoke Mandeville also prompted some to come to its defence last night.

The former television presenter and DJ Sir Jimmy Savile who is a prominent fundraiser and patron of the hospital, said: "We have known about this bug for 18 months and it is under control. The hospital has done everything it can to tackle this problem and people should feel safe about coming here."

Sue Wiseman, the infection control adviser to the Royal College of Nursing, said: "Specialist units like Stoke Mandeville have a particular problem because they have patients being transferred from hospitals up and down the country, adding to the spread of infection. It also has the problem of being an old hospital, rather than a brand spanking new building, which means it has lots of nooks and crannies and can be harder to clean."