Superbug Resistant to Last-Resort Antibiotic Arises in China

A wide variety of E. coli bacteria in China have developed resistance to a key antibiotic of last resort, a new study has revealed, a worrying development in the rise of so-called superbugs.


A second study released Friday, like the first published in the journal Lancet Infectious Diseases, found the superbug is still uncommon in Chinese hospitals—though not a rare as experts might like.

The gene known as mcr-1—which has the capacity to move from one bacterium to another—was found in about 1 percent of E. coli bacteria and 1 percent of a bacteria, known as Klebsiella pneumoniae, that can cause pneumonia, bloodstream infections, and wound infections.

Although that incidence was described as rare, it wasn’t especially reassuring to Lance Price, director of the Antibiotic Resistance Action Center at George Washington University.

“One percent doesn’t sound huge, but for something that we didn’t know about a little more than a year ago and that is clearly a recently evolved [drug resistance] element, it’s pretty substantial,” said Price, who was not involved in the study.

The mcr-1 gene gives bacteria the ability to withstand treatment with a drug called colistin. It’s an old antibiotic that wasn’t used much for years because it has unpleasant side effects; other newer drugs were simply better. But with resistance to better drugs on the rise, colistin has taken on increasing importance in medicine.

In many places is it reserved for human use—and even then, only when absolutely needed. But China has been using it in agriculture, to speed growth of animals raised for meat.

In November 2015 scientists reported finding this gene in China, raising alarms around the world. Within a short span of time researchers elsewhere revealed they had looked for and found the gene in their stored bacteria collections.

An alarming feature of mcr-1 is that the gene moves easily from bug to bug and also from a family like E. coli to others, like Klebsiella pneumoniae.

The authors of the new paper reporting the incidence of the gene in hospital infections are from Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, in Hangzhou.

Professor Timothy Walsh of the University of Cardiff was one of the discoverers of mcr-1 and is also an author of the paper that tracked the gene’s spread among E. coli bacteria.

“I think the takeaway message is that mcr-1 is very, very widely spread among many different types of E. coli and therefore is kind of pervasive, really, throughout Chinese communities,” Walsh told STAT.

And that picture could be about to get a lot worse.


Read more: SA

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