Scientists Have Found Bacteria Resistant To 'Last Resort' Drug

Scientists have discovered a bacteria mutation that they say is resistant to an antibiotic typically considered "the last line of defense" against virulent strains of E. coli and pneumonia. 

In a report published Thursday in The Lancet Infectious Diseases, a U.K.-based medical journal, the scientists wrote that they'd found colistin-resistant bacteria on a Chinese pig farm. Later, they observed the resistant bacteria in raw meat and even humans. 

Colistin, a 50-year-old drug used on animals more than humans, is given to people only when all other antibiotics have proven ineffective. 

The resistant mutation, dubbed the MCR-1 gene, was found in one-fifth of the 804 animals observed. It also showed up in 15 percent of the 523 raw meat samples and in 1 percent of the 1,332 patients observed in the roughly three-year study. 

"The links between agricultural use of colistin, colistin resistance in slaughtered animals, colistin resistance in food, and colistin resistance in human beings are now complete," the researchers wrote.

Based on these findings, the researchers urged countries to reassess their use -- and overuse -- of antibiotics. Wired also published a cheeky-but-grim obituary for the drug.

"One of the few solutions to uncoupling these connections is limitation or cessation of colistin use in agriculture," two of the authors wrote in published comments attached to the study. "Failure to do so will create a public health problem of major dimensions."

Colistin can be toxic to the kidneys, which is why it fell out of favor  for broad human use in the 1970s. But it's still commonly given to livestock around the world to treat or prevent diseases. China, now the world's largest poultry and pork producer , is a heavy user of colistin in livestock. Researchers note that in 2010 the antibiotic was the "fifth most sold group of antimicrobials" in Europe.

"If MRC-1 becomes global, which is a case of when not if, and the gene aligns itself with other antibiotic resistance genes, which is inevitable, then we will have very likely reached the start of the post-antibiotic era, " University of Cardiff professor Timothy Walsh, one of the study's researchers, told the BBC on Thursday.

The research team comprised scientists from China, Australia and the U.K., and the study was funded by China's Ministry of Science and Technology and the National Natural Science Foundation of China.

The scientists noted in their report that while MCR-1 is "currently confined to China," it's likely to spread further if the overuse of antibiotics is not stopped. 

"We must all reiterate these appeals and take them to the highest levels of government or face increasing numbers of patients for whom we will need to say, 'Sorry, there is nothing I can do to cure your infection.'"

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