As if the mere presence of superbugs alone isn't troubling enough, researchers found out that some bacteria are already resistant to the world's last line of antibiotics.

Researchers from China identified a gene in infectious bacteria like Escherichia coli that made them invulnerable to polymyxins, which are considered the last line of defense antibiotics in case all other are ineffective.

This discovery is very troubling, especially since results suggest that this gene can be transferred between bacteria, increasing chances of these resistant superbugs to multiply to the point that it can cause epidemics.

Other bacteria that were found to have the gene include Klebsiella pneumoniae and Pseudomonas aeruginosa, both of which can cause life-threatening pneumonia, blood infections or sepsis.

"Our results reveal the emergence of the first polymyxin resistance gene that is readily passed between common bacteria such as Escherichia coli and Klesbsiella pneumoniae,"said Jian-Hua Liu from the South China Agricultural University and one of the study's lead researchers.

The resistant E.coli strain was first isolated in a pig farm in Shanghai during a routine test.  The bug was able to transfer its immunity to antibiotics to other strains through a mobile gene, leading researchers to also test pork and chicken sold in more than 50 locations across Guangzhou between 2011 and 2014.

Among the tested animals and raw meat samples, there was a high prevalence of E.coli superbugs. 16 E.coli and K. pneumoniae strains were also identified as resistant from more than 1,300 patients.

"These are extremely worrying results... suggesting that the progression from extensive drug resistance to pan-drug resistance is inevitable." Liu said.

Researchers believe that it was the heavy use of antibiotics on these animals that could have contributed to the development of the resistant gene.  Globally, colistin use in agriculture was expected to amount to nearly 12,000 tons annually and may rise up to 16,500 tons by 2021.

China's Ministry of Agriculture has already launched a risk assessment for colistin use in animal feeds.

Other experts in the healthcare field found the discovery very disturbing and alarming, especially the possibility that immunity can be transferred among bacterial strains.  Experts suggest that careful surveillance and research to discover new antibiotics that can work on these resistant strains should be done to prevent a potential global spread of these superbugs.