Scientists are shocked at the speed at which resistance to powerful antibiotics spreads from animals to people.

　　New research has shown that genetic changes in pathogens affect people and animals around the world in just a few years. The research suggests these genetic changes probably spread from a pig farm in China.

　　Professor Francois Balloux is the lead researcher for the study and director of the Genetics Institute at University College London.

　　He says the powerful antibiotic Colistin has become an important last line of defense. It is used to save people's lives when all other drugs have failed.

　　"And it was mostly used in agriculture then, in pigs and a bit in chickens. But recently, as we are running out of drugs, people actually have become a bit more interested in using it, and it has been used quite extensively recently over the last five to 10 years in the clinic."

　　Now, even Colistin is losing its power against highly resistant bacteria called "superbugs."

　　Fast mutation

　　Deadly pathogens like E. Coli or salmonella can change and develop resistance to antibiotics. Balloux's research identifies the speed at which the gene that gives resistance to Colistin began in the mid-2000s.

　　"It happened once. And it jumped very, very likely from pigs, probably in China, and it spread extremely rapidly throughout the world. And it also spread in all sorts of different species and affects humans."

　　The resistance has even been found in pathogens in seawater on Brazilian beaches. Balloux notes his study centered on just one resistant gene, but many pathogens are developing other forms of resistance.

　　Sally Davies is Britain's chief medical officer. She warned recently that anti-microbial resistance could lead to the "end of modern medicine."

　　Last October, she spoke to delegates at a conference on anti-microbial resistance in Germany. She told them that common operations, such as cesarean sections, would become dangerous without working antibiotics.

　　"Those would become much more risky if we did not have effective antibiotics. Superbugs kill and they're on the rise."

　　Scientists are working on improving existing drugs like Colistin to give them added power against resistant pathogens.

　　In the longer term, researchers say more investment is needed in developing new drugs. They also say there is a need to rethink how antibiotics are used in agriculture and at clinics.

　　I'm Alice Bryant.

　　Henry Ridgwell wrote this story for VOA News. Alice Bryant adapted it for Learning English. Hai Do was the editor.