New superbug could be epidemic, scientists find

Expert urges strict regulations on use of antibiotics, further research

Chinese scientists have discovered a new drug-resistant strain of bacteria that can spread stealthily and has epidemic potential.

The superbug is a strain of Salmonella typhimurium whose plasmid - mobile DNA that can be easily copied and shared between bacteria - contains the MCR1.6 gene, a newly discovered variant of the drug-resistant MCR1 gene.

"This is the first time the MCR1.6 gene has been found in Salmonella, a common foodborne pathogen, and from a healthy carrier," said Kan Biao, deputy director of the Chinese Center for Disease Control and Prevention's National Institute for Communicable Disease Control and Prevention.

MCR1 and its variants could help bacteria resist polymyxins - a last-resort class of antibiotics that includes colistin, the most potent, but toxic, antibiotic - according to studies by the institute, the results of which were published this month by Antimicrobial Agents and Chemotherapy, a journal produced by the American Society for Microbiology.

Bacterial infections caused by the MCR1 gene and its variants are treatable with other antibiotics, "but often at the cost of killing good bacteria and breaking the body's microflora balance", Kan said.

Kan's team first discovered the MCR1.6 gene in a 2014 fecal example of a 46-year-old woman from the Guangxi Zhuang autonomous region.