Some types of anti-bacterial wipes used by hospital staff to clean surfaces could be helping to spread bacteria, researchers say.
The Welsh School of Pharmacy found that MRSA survived on the wipe, and then contaminated everything it touched.
The team said staff should throw away wipes after cleaning just one surface.
An infection-control specialist said killing bacteria instantly was not as vital as the need to tackle the dirt and debris on which they thrived.
What is remarkable is that some of these wipes actually have the words 'kills MRSA' written on the box
Dr Gareth Williams
Welsh School of Pharmacy
Dr Gareth Williams, who is presenting the research at the American Society of Microbiology's Annual Meeting in Boston, said he planned to share his full findings with infection control teams.
He visited the intensive care units of Welsh hospitals to watch how staff used wipes, and found it was common for a single wipe to be employed on more than one surface.
"What I found was that staff would wipe one thing, perhaps a bed rail, then move on to several other surfaces, so we went back to the laboratory to see how different wipes performed under these conditions."
He discovered that while wipes were quite good at picking up bacteria from the first surface, they were unable to kill off that bacteria swiftly.
This meant that the subsequent cleaning using the same wipe resulted in contamination.
One use only
Dr Williams said: "What is remarkable is that some of these wipes actually have the words 'kills MRSA' written on the box.
"We found that, under the conditions we observed in actual hospitals, this wasn't the case."
He said that hospital staff should be taught not to clean more than one thing with the same wipe, even if it was advertised as 'anti-bacterial'.
Tracey Cooper, a nurse consultant and spokesman for the Infection Prevention Society, welcomed the research, but said that there were reasons why the ability of a wipe to destroy MRSA quickly was not a top priority.
"If they did contain an agent sufficiently powerful to kill bacteria instantly, the chances are it would be very bad for your hands," she said.
"The human body is beautifully designed for spreading things like MRSA, and if one surface in a room is contaminated with MRSA, it is likely that other surfaces nearby will also be contaminated.
"The important thing when cleaning is to physically remove bacteria, and the dust and dirt on which they live.
"In addition, staff are generally taught that you start wiping the surface that is most likely to be clean, and finish with the surface that is most likely to be dirty."
A Department of Health spokesman said: "The use of anti-microbial wipes is not counter-productive; we have robust protocols and it is important that staff follow them."