You Want Superbugs With That?
Stuart Levy once kept a flock of chickens on a farm in the rolling countryside west of Boston. No ordinary farmer, Levy is a professor of molecular biology and microbiology and of medicine at Tufts University School of Medicine. This was decades ago, and his chickens were taking part in a never-before-conducted study. Half the birds received feed laced with a low-dose of antibiotics, which U.S. farmers routinely administer to healthy livestock -- not to cure illness, but merely to increase the animals’ rates of growth. The other half of Levy’s flock received drug-free food.
Results started showing up almost instantly. Within two days, the treated animals began excreting feces containing E. coli bacteria that were resistant to tetracycline, the antibiotic in their feed. (E. Coli, most of which are harmless, normally live in the guts of chickens and other warm-blooded animals, including humans.) After three months, the chickens were also excreting bacteria resistant to such potent antibiotics as ampicillin, streptomycin, carbenacillin, and sulfonamides. Even though Levy had added only tetracycline to the feed, his chickens had somehow developed what scientists now call "multi-drug resistance" to a host of antibiotics that play important roles in treating infections in people. More frightening, although none of the members of the farm family tending the flock were taking antibiotics, they, too, soon began excreting drug-resistant strains of E. coli.
When Levy’s study was published in The New England Journal of Medicine in 1976, it was met with skepticism. "The other side -- industry -- could not believe that this would have happened. The mood at the time was that what happens in animals does not happen in people," said Levy, who serves as president of the Alliance for the Prudent Use of Antibiotics, in a telephone interview from his office at Tufts. "But we had the data. It was obvious to us even then that using antibiotics this way was an error and should be stopped."
During the intervening 35 years, study after study has confirmed Levy’s findings and shown that the problem of antibiotic-resistant "superbugs" is even worse than anyone could have imagined. Each year, 70,000 Americans in U.S. hospitals die from bacterial infections that drugs are unable to kill. And even as the number of infectious diseases is on the rise, more antibiotics are administered to livestock than ever before, from 17.8 million pounds per year in 1999 according to the Animal Health Institute (a trade organization of companies, like Bayer, Novartis, and Pfizer, that manufacture livestock drugs) to 29.8 million pounds in 2009, according to the U.S. Food and Drug Administration, or FDA. Fully 80 percent of the antibiotics used in the United States are given to livestock, and the vast majority are administered to promote growth and stave off potential infections, not to treat illness.
From his perspective of more than three decades as a resistant-microbe watcher, Levy sounded almost weary when he said, "Proponents of growth promotion keep asking for more data, and we scientists provide them. But then the findings have never led to removal of the practice."
Earlier this week, the Natural Resources Defense Council, Center for Science in the Public interest, Food Animal Concerns Trust, Public Citizen, and the Union of Concerned Scientists joined forces to file a lawsuit against the FDA. The groups want the agency to withdraw its approval for most non-therapeutic uses of penicillin and tetracycline in animal feed. They say that it’s something regulators should have done decades ago.
The FDA first approved the use of low-dose antibiotics in the 1950s. Concerns about the drugs began appearing within a decade, and by the time Levy’s paper was published, the FDA was aware the practice posed a serious risk to human health. The agency proposed to withdraw its approval in 1977, saying that new evidence showed that penicillin- and tetracycline-containing products had not been "shown safe for widespread, sub-therapeutic use."
The proposal drew howls of outrage from two of the most powerful lobbying groups in Washington, agribusinesses and drug manufacturers. Both the House and Senate ordered the FDA to "hold in abeyance any and all implementation of the proposal" until further studies had been conducted. "It was the power of the lobby and the money behind that lobby," Levy recalled.
As requested by Congress, the FDA commissioned three studies during the 1980s, all of which supported initial concerns about the risks of feeding farm animals antibiotics on a daily basis. The FDA received petitions urging it to act from coalitions of scientific and environmental groups in 1999 and 2005. Such respected bodies as the American Academy of Pediatrics, the Centers for Disease Control and Prevention, the National Academy of Sciences, the U.S. Department of Agriculture, and the World Health Organization all identified low-dose antibiotics as the reason antibiotic-resistant bacteria were proliferating in humans and animals. And the FDA -- which is charged with protecting the health of Americans -- failed to act, only going so far as to issue a "Draft Guidance" report and a draft "Action Plan" proposing voluntary guidelines. These suggestions have done nothing to stem the deluge of unnecessary antibiotics through the spigot of agribusiness.
"We’ve been fighting the non-therapeutic use of antibiotics in livestock for more than 30 years," Margaret Mellon, director of the food and environment program at the Union of Concerned Scientists, said in a press release announcing the lawsuit. "And over those decades the problem has steadily worsened. We hope this lawsuit will finally compel the FDA to act with an urgency commensurate with the magnitude of the problem." (Siobhan Delancey, a spokeswoman for the FDA, declined to comment on the suit.)
The Trouble with Antibiotics
Bacteria are evolutionary dynamos. Untold trillions of them can live in one confined animal feeding operation, or CAFO -- the technical term for a factory farm. They breed rapidly and mutate readily. Exposure to even miniscule levels of drugs equips bacteria with the genetic resilience to fend off higher levels of the same drugs.
From the dawn of modern antibiotics, researchers have been aware that the seeds of the wonder drugs’ destruction had already been sown. In his 1945 Nobel acceptance speech for his discoveries related to penicillin, Sir Alexander Fleming said, "There is a danger that the ignorant man may easily under-dose himself and by exposing his microbes to non-lethal quantities of the drug make them resistant." Fleming’s prediction was prescient -- except the problem wasn’t an "ignorant man" but politicians and business executives whose priorities lay elsewhere.
During the decades that the FDA dithered, a mountain of scientific research accumulated showing that antibiotic-resistant bacteria can not only evolve in the guts of farm animals, but can spread from animals to the humans who tend them, and then be passed on to people who have never been anywhere near a chicken house or hog barn.