Colistin-Resistant Bacteria Now Found In Humans, Evolved In Chinese Pigs

pigs are a vector for disease and harbor antibiotic resistant bacteria

Thank China’s Overuse of Antibiotics for a New Colistin-Resistant Bacteria

Eighteen months ago a gene that makes bacteria resistant to the drug colistin—an antibiotic of “last resort”—was discovered in bacteria infecting Chinese pigs.

Since then this gene, called mcr-1, has proliferated around the world’s farm animal populations at an alarming rate.

According to the American Society for Microbiology, some animal populations harbor enough of the bacteria to make treatment with colistin alone ineffective—drug cocktails are increasingly needed to treat animals.

Worse still, this gene has been found in bacteria living in humans.

A new study conducted in Guangzhou, China, examined the presence of the gene mcr-1 in bacteria living in the human gut.  They found that 497 people, out of 8,000 sampled, harbored colistin-resistant bacteria.

Not only that, but 10% of these bacteria were also resistant to other commonly used antibiotics—they were true superbugs.

This is bad news, even though colistin is rarely prescribed to humans because it causes kidney problems.


Because its infrequent use made it particularly effective at treating drug-resistant pathogens.

You may be wondering why it always seems that drug resistant germs originate in China.  Well, it’s because most of them do.

China is a breeding ground for drug-resistant microbes for two reasons.

First, China loves eating pork.  This means they farm a lot of pigs.

As it turns out, pigs share a surprising amount of genetic material with humans, and are infected by many of the same diseases.  This means that microbes which evolve antibiotic resistance in pigs (which are treated with antibiotics to keep them healthy) can jump to humans much more easily than those that evolve in other animals, like birds.

Remember swine flu?

Second, the Chinese are fiends for antibiotics—they over-prescribe.

For example, according to the British Medical Journal Chinese doctors prescribe roughly ten-times the anti-biotic dosage that American doctors do.

In fact, China uses over half of all the world’s antibiotics each year, despite being home to only 18% of the world’s population.

Sadly, even if China cuts back their antibiotic use significantly, the damage has already been done.

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