The British Medical Association has called for 'hard data' on the effectiveness of screening all hospital admissions for MRSA.
The demand comes in response to Lord Darzi's call for MRSA screening for all planned admissions from next year and for all emergency admissions as soon as possible in the next three years.
But a sceptical BMA questioned the recommendation, which would mean screening 4 million elective admissions a year in England.
BMA, head of science and ethics Vivienne Nathanson said: 'We need hard data showing such an initiative would be effective.'
She added that it was crucial that patients understood the reasons for screening and that those testing positive were not denied treatment.
MRSA screening is used in some Scandinavian countries where it is said to have cut infection rates dramatically. Some English hospitals are also screening patients.
NHS Quality Improvement Scotland has launched a pilot project to look at the cost and benefit of MRSA screening. It would see 1 million patients screened a year at a cost of£55m for three years. MRSA costs the Scottish NHS£183m a year.