A new gene that makes bacteria highly resistant to a last-resort class of antibiotics has been identified in China, and doctors are warning of the global implications.

"These genes could result in infections that are very difficult to treat in humans," explains Dr. Ritu Banerjee, a Mayo Clinic pediatric infectious diseases expert.

The gene, called MCR-1, makes bacteria resistant to a class of known as polymyxins, which are antibiotics of last resort, used to fight superbugs. The discovery is described as "alarming" by scientists quoted in a Reuters article. They call for urgent restrictions on the use of polymyxins, a of antibiotics that includes the drug colistin, widely used in livestock farming.

"Our findings emphasize the urgent need for coordinated global action," researchers said in a published summary of their research.

Dr. Banerjee agrees. "The fact that it has just been found in China doesn't mean that we are safe from that here. International travel and global food supply networks mean that anywhere in the world can be spread to the United States."

An expert at the U.S. Centers for Disease Control, quoted on the website STAT, says if the resistance spreads, it will seriously limit the treatment options available to doctors facing antibiotic-resistant infections.