Hospitals in large cities act as breeding grounds for the superbug MRSA before it spreads across the country, a study has revealed.

Researchers have found evidence that variants of the potentially deadly infection found in smaller regional hospitals probably originated from larger city hospitals. The University of Edinburgh study looked at the genetic make-up of around 80 variants of a major clone of MRSA found in hospitals.

Paul McAdam, an author of the research paper, said: "Our findings suggest that the referral of patients to different hospitals is a major cause of MRSA transmission around the country. This knowledge could help in finding ways to prevent the spread of infections."