Pig MRSA

Janice Haney Carr / Centers for Disease Control and Prevention

Researchers connected with Northern Arizona University have discovered the origins of a strain of anti-biotic resistant staph.

Their new study appeared this week in the on-line journal mbio, published by the American Society of Microbiology..

The bacterium started in humans, moved to animals, then moved back to humans again.

And in the course of its journey, it developed its resistance to antibiotics.

First some basic terms.

Staphylococcus aureus, or staph, is a common bacterium.