The MRSA superbug

All 40 hospitals with the worst rates of MRSA (methicillin resistant staphylococcus aureus) were classed as either green or amber under the government's traffic-light grading system for hospital cleanliness.

None received the red rating, which would have indicated they needed to improve.

An estimated 5,000 people die from hospital -acquired infections such as MRSA each year.

MRSA is stopped by infection control, such as nurses washing their hands between patients Department of Health spokeswoman

The Liberal Democrats looked at 20 specialist and 20 acute hospitals with the highest rates of infection of MRSA.

Twenty-eight were classified as green and 12 as amber.

'Failure'

The Liberal Democrats say only one of 19 targets in the clean hospital programme relates to ward cleanliness and none relate to the prevention and spread of infection.

Paul Burstow, Liberal Democrat health spokesman, said: "The clean hospital programme should be prosecuted under the trade description act. It is nothing of the sort.

"It is giving patients and families a false sense of security that the government is on top of the superbug problem when ministers have not even begun to tackle the virus.

"Ministers must stop peddling the idea that they are on top of this problem and acknowledge the human cost of their failure."

Dr Liam Fox, Shadow Health Secretary, said: "Patients will think its outrageous that hospitals with the highest infection rates should be given top marks for cleanliness. It's absurd."

Blood poisoning

But a spokeswoman for the Department of Health said having cleaner hospitals and reducing MRSA rates were completely different aims.

"Clean hospitals are about the cleanliness of the floors, clean linen and clean toilets - that doesn't affect MRSA rates.

"MRSA is stopped by infection control, such as nurses washing their hands between patients.

"You can't look at one and extrapolate something about the other. They are not looking at the same thing."

Staphylococcus aureus is a bacterium that lives harmlessly on the skin and in the nose of about one third of normal healthy people.

It only causes problems when it gets into the body, which is more likely to happen when people who ill.

It can cause abscesses or infect wounds, and may then spread into the body and cause serious infections such as blood poisoning.