Midlothian scientists have discovered that a type of MRSA found in humans originated in cattle at least 40 years ago.
The Roslin Institute researchers studied the genetic make-up of more than 40 strains of a bacterium.
At least two genetic subtypes of the bacterium, which have become endemic in people, have been traced back to cattle.
Lead researcher Professor Ross Fitzgerald said: “Human infections caused by bacteria being transmitted directly from livestock are well known to occur.
“However, this is the first clear genetic evidence of subtypes, which jumped from cattle and developed the capacity to transmit widely among human populations.”
The study, published in the journal mBio, also involved Danish researchers.