Virulent bugs are spreading outside hospitals and in the community and may put lives at risk, experts say.
They want doctors to be alert to a potentially lethal form of MRSA which can infect the lungs, and may strike young people in particular.
Panton Valentine leukocidin (PVL) strains of community-acquired MRSA can cause a condition called necrotizing pneumonia, which destroys lung tissue.
This only affects a minority of those infected, but can be deadly.
The condition is spread outside of hospitals via skin-to-skin contact and appears as sores which look like insect bites. In the very worst cases, it can kill in a day.