An article in mBio, published by the American Society for Microbiology, says that antibiotic use in pigs is responsible for making a strain of MRSA found in livestock immune to antibiotics.
That strain of MRSA then jumped back into the genome armed with the new resistance to drugs that once were able to treat it.
Livestock are fed hormones and antibiotics to combat infection and help them grow faster in crowded spaces where they are raised. Opponents say this overuse of antibiotics can force microbes like MRSA to mutate.
MRSA is a painful infection that begins on the skin as a boil that can progress into a painful skin abscess leading to life-threatening infections in bones, joints, surgical wounds, the bloodstream, heart valves and lungs.
Cooking food thoroughly can kill MRSA found in beef and pork products.