The mcr-1 gene that helps treat bacteria against colistin – one of the few antibiotics still used as a last resort – has now reached hospitals around the world.
And thanks to new research, we now have more evidence of where it comes from – pig farms in China.
While experts had previously believed that the gene was in Chinese pig farms due to their extensive use of colistin on The latest study provides more evidence to support this idea.
It shows the beginning of the spread to sometime in 2005.
Although there is nothing good about the increase of MCR-1 and antibiotic resistance in general, the genetic analysis techniques used in this research could help scientists to better manage the distribution of superbugs in the future.
"The speed with which MCR-1 is spreading worldwide is indeed shocking," says lead researcher Francois Balloux from University College London (UCL) in the United Kingdom  Genomes of 110 bacterial strains and comparing them with existing genomic data, the team identified a large data set of 457 mcr-1 positive genome sequences, distributed by humans and farm animals on five continents.
This allows them to show exactly where MCR -1 had crystallized and how it spread globally – attaching to various bacterial pathogens by "hitchhiking" on various mobile genetic elements
"By decoding the genetic code of these bacteria, we could not only predict how and where, but also when mcr-1 began to spread," says one of the researchers, Lucy van Dorp of UCL.
"This is so important because the presence of MCR-1 around the world in many different bacterial species in just a decade underlines the ease and speed with which these resistant genes can be spread."
Now that we are able to track how mcr-1 is spreading, we could better prepare ourselves for the next antimicrobial resistance gene (AMG). That will require global effort and cooperation between countries, the researchers say.
Because of its potential serious side effects, colistin is only used as the last antibiotic for infections such as E. coli but the proliferation of Mcr-1 makes it ineffective.
The gene can bounce between bacteria of different species, making it very difficult to stop.
As hospitals continue to warn against the rise of superbugs and experts, the situation will gradually worsen. Scientists are looking for ways to improve our medicines to meet the challenge. DNA sequencing could be one way to do that.
"Given the lack of new antibiotics in the pipeline, our greatest hope for avoiding the current public health crisis is exploiting the potential of bacterial genome sequencing and translating it into improved monitoring and diagnostic tools," says Balloux.
The results were published in Nature Communications .