MRSA, the bug that thrives in hospitals, is now a bigger killer in the USA than AIDS.
It killed 18,650 people in American hospitals in 2005, the latest year when figures were available. In the same year, 18,000 people died from AIDS in North America, including Canada.
Experts believe the MRSA rate has increased dramatically since then.
Although half the people died at home, researchers believe they caught the bug while they were in hospital.
(Source: Journal of the American Medical Association, 2007; 298: 1763-71).