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Superbugs might become an even larger and more threatening public health problem in the future.

Chinese scientists have reportedly identified a gene that makes Enterobacteriaceae, a family of gram-negative bacteria, resistant to "last-resort" drugs known as polymyxins. The team stated that the bacteria with the mcr-1-gene could be found in pigs and people residing in south China.

"These are extremely worrying results," study author Jian-Hua Liu, a professor at South China Agricultural University in Guangzhou, China, reported by HealthDay via Philly.com. "The polymyxins (colistin and polymyxin B) were the last class of antibiotics in which resistance was incapable of spreading from cell to cell. Until now, colistin resistance resulted from chromosomal mutations, making the resistance mechanism unstable and incapable of spreading to other bacteria."

The researchers reported that since the gene was found on plasmids, there is a higher chance that it can spread to other types of bacteria, causing more strains to become drug-resistant. Plasmids, which are DNA molecules, increase the gene's likelihood of being copied and transferred to other bacteria because of their mobility.

The team did not uncover how this particular gene developed but the researchers argued that wide use of antibiotics on farm animals could be the culprit. In China, farmers tend to use polymyxin colistin on pigs and other livestock.

"The emergence of mcr-1 heralds the breach of the last group of antibiotics," Liu's team wrote. "Although currently confined to China, mcr-1 is likely to emulate other resistance genes ... and spread worldwide. There is a critical need to re-evaluate the use of polymyxins in animals and for very close international monitoring and surveillance of mcr-1 in human and veterinary medicine."

The team noted that certain strains could lead to potentially dangerous epidemics. They added that the Chinese government will be investigating the risks involved with using colistin in agriculture.

"All use of polymyxins must be minimized as soon as possible and all unnecessary use stopped," Laura Piddock, a professor of microbiology at Britain's Birmingham University, commented reported by FOX News.

The study as published in the journal, The Lancet Infectious Diseases.