Apocalypse Pig: The Last Antibiotic Begins to Fail
I mentioned on Monday that this past week was intended by the CDC, WHO and other health authorities to be a global awareness week for antibiotic resistance. Alarming news that came out of China at the end of the week certainly created new awareness of resistance, but possibly not what the organizers had in mind.
On Thursday, researchers from several Chinese, British and US universitiesannounced in the journal Lancet Infectious Diseases that they have identified a new form of resistance, to the very last-ditch drug colistin—and that it is present in both meat animals and people, probably comes from agricultural use of that drug, can move easily among bacteria, and may already be spreading across borders.
This is very bad news.
To understand why, it’s necessary to know a little bit about colistin. It is an old drug: It was first introduced in 1959. It has been on the shelf, without seeing much use, for most of the years since, because it can be toxic to the kidneys. And precisely because it hasn’t been used much, bacteria have not developed much resistance to it. It remains effective.
That neglect turned out to be very fortunate a few years ago when several different resistance factors—NDM, OXA, KPC—started hopscotching around the globe. All of them made bacteria invulnerable to a group of drugs called carbapenems that had been considered a last line of defense: They were the last drugs that were in common use and were able to take care of complex infections that happen in hospitals, caused by E. coli, Klebsiella, Acinetobacter and similar gut-dwelling organisms. Once those bacteria became resistant to carbapenems (earning them the general name of “carbapenem-resistant Enterobacteriaceae,” or CREs), colistin was all that was left—and colistin use began rising.
(From around that time: Here’s a great story that Jason Gale of Bloomberg wroteabout colistin, and one I wrote for Nature about CREs. A long series of posts I wrote for WIRED about the discovery of NDM and the bitter political fights over its apparent origin in India can be found here. Of note, one of the discoverers of NDM is one of the authors of this new research.)
A thing about colistin, which no one seems to have connected the dots on: Because it is an old drug, it is cheap. And because it is cheap, it is an affordable addition to animal feed for all the uses I’ve talked about before: to make animals put on muscle mass faster, and protect them from the conditions of intensive farming.
Which, apparently, is how it is being used in China—but not only in China. From the paper:
China is… one of the world’s highest users of colistin in agriculture. Driven largely by China, the global demand for colistin in agriculture is expected to reach 11,942 tonnes per annum by the end of 2015 (with associated revenues of $229·5 million), rising to 16,500 tonnes by the year 2021, at an average annual growth rate of 4·75%. Of the top ten largest producers of colistin for veterinary use, one is Indian, one is Danish, and eight are Chinese. Asia (including China) makes up 73·1% of colistin production with 28·7% for export including to Europe.
The findings reported this week originate in an ongoing project in which the Chinese authors were looking for resistance in the E. coli that reside in the guts of food animals. (It’s encouraging that
FOR ENTIRE ARTICLE CLICK LINKClick here for the Top 12 Moments in Jewish History...LET THE ADVENTURE BEGIN! »