A new gene that makes bacteria highly resistant to a last-resort class of antibiotics has been found in people and pigs in China – including in samples of bacteria with epidemic potential, researchers said on Wednesday.

The discovery was described as “alarming” by scientists, who called for urgent restrictions on the use of polymyxins – a class of antibiotics that includes the drug colistin and is widely used in livestock farming.

“All use of polymyxins must be minimised as soon as possible and all unnecessary use stopped,” said Laura Piddock, a professor of microbiology at Britain’s Birmingham University who was asked to comment on the finding.

Researchers led by Hua Liu from the South China Agricultural University who published their work in the Lancet Infectious Diseases journal found the gene, called mcr-1, on plasmids – mobile DNA that can be easily copied and transferred between different bacteria.

This suggests “an alarming potential” for it to spread and diversify between bacterial populations, they said.

The team already has evidence of the gene being transferred between common bacteria such as E.coli, which causes urinary tract and many other types of infection, and Klesbsiella pneumoniae, which causes pneumonia and other infections.

This suggests “the progression from extensive drug resistance to pandrug resistance is inevitable,” they said.

“(And) although currently confined to China, mcr-1 is likely to emulate other resistance genes … and spread worldwide.”