The proportion of adult carriers could be even higher. The superbugs are no immediate threat to those carrying them, but could cause dangerous infections after an operation, for example.
Carriers can also infect other people.
The finding has serious public-health implications, warns Michael Millar of Bart's and the Royal London School of Medicine, the study's author. This may be just the beginning of something that will take off in a big way. We need policies to control antibiotic resistance that go across boundaries. Marcos Espinal, leader of the World Health Organization's surveillance project on drug-resistant tuberculosis, agrees. Gene swap Superbugs such as MRSA are already a big problem in hospitals, but relatively little is known about the extent of resistance in the healthy population.