THE REMARKABLE advances in genomics have provided an ever-more-startling view of life’s basic mechanics. Just in recent days, scientists sleuthing through huge databases unearthed a worrisome discovery: A mobile gene that can help bacteria resist antibiotics has spread to many more countries than previously realized. The good news is that technology is pulling back the curtain. The bad news is that the problem of antibiotic resistance has opened a new front.
Ever since humans developed antibiotics in earnest more than half a century ago, bacteria have been finding ways to resist the drugs. For several decades it was possible to stay ahead of this trend by finding new antibiotics. But then the pace of innovation slowed, and bacteria evolved methods to resist more and more antibiotics. Without these drugs, some diseases can become untreatable.
In November and December, researchers in China and Denmark reported discovering evidence of resistance to the antibiotic colistin. A relatively old antibiotic with toxic side effects, colistin has been used for human health in the United States — when other antibiotics don’t work, colistin is sometimes deployed as a last resort — and it has been used on farm animals overseas. The resistance mechanism to colistin was carried on a plasmid, a kind of bus for genetic material, given the designation MCR-1 that can be transferred from one bacterium to another.
Only weeks after the reports from China and Denmark, a slew of new MCR-1 sightings appeared in the journal the Lancet Infectious Diseases. In France, scientists looked at 517 isolates from veal calves taken from 2005 to 2014 on 94 widely distant farms. They found MCR-1 on 21 percent of them and estimated that the dissemination happened a decade ago. In Germany, researchers looked at 577 isolates since 2009 and found evidence of MCR-1 in three swine and one human . “Our data suggest that the advent of untreatable infections has already arrived,” they declared, because every bacteria resistant to colistin was also resistant to more modern antibiotics. There were similar reports from scientists checking data from animals and people in Japan, Vietnam, Switzerland, Belgium and elsewhere.
This kind of forensic examination is revelatory but not the last word. The agriculture industry has long defended giving antibiotics to healthy animals to help them grow larger and faster, saying that the practice does not contribute to resistance to antibiotics important to human health. But the latest findings suggest humans and other animals are not so easily separated when it comes to antibiotic resistance. It also suggests that relatively older antibiotics, like colistin, can lead to resistance that undermines more modern antibiotics vital to human health. Antibiotics have for too long been overused in both human health and animal agriculture, and the new research is yet another reason to insist these valuable drugs be dispensed more judiciously — everywhere.