Scientists have warned dog owners in the UK about a superbug which can kill humans.
The mcr-1 gene is believed to transfer from animals to humans and it can build resistance to life-saving drugs.
Drug-resistant infections are estimated to kill 700,000 people a year across the world.
And the WHO says drug-resistant diseases could cause 10 million deaths each year by 2050 if left unchecked, the Daily Express reports.
The mcr-1 gene was first reported in China in 2015 and is resistant to colistin, an antibiotic used to defeat bacterial infections which other drugs can not tackle.
Scientists urge people not to regularly share beds with domestic dogs - which can harbour mcr-1 - which is in the gut and transported via microscopic fecal particles.
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A study at the University of Lisbon discovered that in two of the households where dogs had tissue infections the mcr-1 gene was present in both the dog and owner.
Fecal samples were taken from 126 healthy people living with 102 cats and dogs in 80 households over the two years up to February 2020.
Results confirmed that eight of the dogs and four humans were found to be harbouring bacteria including mcr-1.
Three of the dogs appeared to be healthy, the others having tissue or urinary tract infections.
The study was presented at the European Congress of Clinical Microbiology and Infectious Diseases conference this weekend.
Experts said that agricultural regions that use colistin, particularly southern European countries, will be less likely to contract the mcr-1 gene.
Dr Juliana Menezes, who led the research, said: “Colistin is used when all other antibiotics have failed, it is a crucial treatment of last resort.
“If bacteria resistant to all drugs acquire this resistance gene, they would become untreatable, and that’s a scenario we must avoid at all costs.
“We know that the overuse of antibiotics drives resistance and it is vital that they are used responsibly, not just in medicine but also in veterinary medicine and in farming.”
A separate study also revealed that owners who feed their pets certain types of raw dog food containing high levels of colistin is a major source of antibiotic-resistant bacteria.
For years experts have warned that too much colistin can lead to more mutant genes meaning the drug will be ineffective on humans.
Researchers at the University of Porto analysed samples from a range of types of dog food, finding that 54 percent contained the bacteria Enterococci.
This means a quarter of the samples with Enterococci were resistant to linezolid, another last-resort antibiotic.
Dr Ana Freitas, who conducted the research, said: “The close contact of humans with dogs and the commercialisation of the studied brands in different countries poses an international public health risk.
“European authorities must raise awareness about the potential health risks when feeding raw diets to pets and the manufacture of dog food, including ingredient selection and hygiene practices, must be reviewed.
