Researchers have nailed down something scientists, government officials and agribusiness proponents have argued about for years – whether antibiotics in livestock feed give rise to antibiotic-resistant germs that can threaten humans.
A study in the journal mBio, published by the American Society for Microbiology, shows how an antibiotic-susceptible Staph germ passed from humans into pigs, where it became resistant to the antibiotics tetracycline and methicillin. And then the antibiotic-resistant Staph learned to jump back into humans.
"It's like watching the birth of a superbug," says Lance Price of the Translational Genomics Research Institute, or TGen, in Flagstaff, Arizona.
Price and colleagues in 19 countries did whole-genome analysis on a Staph strain called CC398 and 88 closely related variations. CC398 is a so-called MRSA, or methicillin-resistant Staphylococcus aureus, that emerged within the past decade in pigs and has since spread widely in cattle and poultry as well as pigs.