That means they're basically invincible. And MCR-1 could theoretically end up jumping to all manner of bacteria.
"Polymyxins were the last class of antibiotics in which resistance was incapable of spreading from cell to cell," co-author Jian-Hua Liu, a professor at Southern Agricultural University in Guangzhou, told the AFP.
So much for that.
The researchers tested slaughterhouse pigs and raw meat from markets for the gene. MCR-1 was found in 20 percent of the sampled pigs and 15 percent of the meat, and in increasing abundance from year-to-year. The gene was also found in E. coli K. pneumoniae samples taken from 16 of 1,322 patients at two Chinese hospitals.
The results are troubling, to be sure. But they're not surprising. We're actually in the midst of the first-ever World Antibiotic Awareness Week — a campaign by the World Health Organization to convince the public to treat antibiotics as a precious, depleting resource. Antibiotic resistant bacteria is already implicated in at least 700,000 deaths per year worldwide, and some estimate that the death toll could skyrocket to 10 million per year by 2050, if trends continue.
A recent report found that most members of the public don't even really understand what antibiotic resistance means.
It's a simple equation: The more antibiotics that are used, the more bacteria are exposed to them and have the chance to evolve resistance. If we don't conserve our antibiotic usage, we'll quickly run out of antibiotics that actually work.
Polymyxins are meant to be reserved for dire medical cases — after all, these drugs are too toxic for a human to want to consume. But in China, their rare usefulness in humans has led to a secondary use: animal husbandry. Chinese pigs are some of the biggest consumers of the drug colistin, a kind of polymyxin, which is used to fatten them up. The researchers report that this is almost certainly the breeding ground of the resistance, and that the Ministry of Agriculture has launched an investigation to assess this.
We may not have ruined colistin on pigs in the United States, but we're on a path to do the same with other antibiotics. An estimated 70 percent of the antibiotics important to health are used in livestock in the United States. We may not be throwing away our last line of defense, but we're whittling away at our day-to-day treatment options — making it more likely that we'll need harsh drugs like colistin.