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By David Wallinga

Scientists and regulators have sounded the alarm linking the overuse of antibiotics in livestock production with helping to increase the creation and spread of antibiotic resistant infections. Three years ago, as a result, the U.S. Food and Drug Administration (FDA) launched a voluntary program seeking to curb some livestock drug uses. But the widespread use of these antibiotics seems to continue as before.

On Thursday, the latest FDA figures on antibiotics sold for use in meat and poultry production came out. The news is not good. Sales just keep rising. Against the backdrop of a crisis in now untreatable or nearly untreatable infections, this report further underscores how urgently we need more and stronger government action to address the ongoing overuse of the drugs in livestock.

Sales of medically important antibiotics—including penicillins, cephalosporins, tetracyclines and erythromycins, to name a few—for livestock were up 2 percent over 2014, and up 26 percent overall from 2009 through 2015. An overwhelming 95 percent of human antibiotics were sold as additives to animal feed and drinking water—routes of delivery that are typical of growth promotion or disease prevention.

More than 21.3 million pounds of medically-important drugs were sold for use in livestock last year. By comparison, the FDA reports that in 2011 (the last year for which it has such data, apparently) a bit more than 7.2 million pounds of antibiotics were sold for use in human medicine. In other words, just under 70 percent of all medically important antibiotics in the U.S. are sold for use in animals, not people. In 2015, 97 percent of all medically important antibiotic sales for livestock or poultry were over-the-counter, meaning they were sold without a prescription and typically without any oversight by a veterinarian.

It remains unclear how effective FDA's current voluntary efforts will be to reduce the routine use of antibiotics in livestock and poultry production. While livestock antibiotics will no longer carry a label that says they can be used for growth promotion, many of these same products will continue to be approved for routine use in the same manner and similar dosages for the purpose of disease prevention. The pharmaceutical industry has consistently claimed that "growth promotion" constitutes no more than 10 percent of antibiotic use in livestock and poultry. The Natural Resources Defense Council believes that the use of antibiotics in animal feed or water under a "disease prevention" claim constitutes the vast majority of all antibiotic use.

Two million Americans already suffer from drug-resistant infections every year and more than 23,000 die as a result, according to the Center for Disease Control and Prevention. My New Year's resolution would be for antibiotics to be used differently in the future, especially in livestock production. One might have thought sales figures would already be dropping, since every food animal sector claims they're using fewer antibiotics and only when medically justified. But the FDA's actual data suggest otherwise.

David Wallinga is the senior health officer at the Natural Resources Defense Council.

By David Wallinga

Not all bacteria are created equal. The first-time discovery of a long-dreaded superbug on U.S. pig farms, announced Monday, really stands out. And not in a good way.

What they found on pig farms was a kind of CRE bacteria, for carbapenem-resistant Enterobacteriaceae. CRE is one of the nastier superbugs. Infections with these germs are very difficult to treat and can be deadly—the death rate from patients with CRE bloodstream infections is up to 50 percent.

The Centers for Disease Control and Prevention (CDC) said these bacteria already cause 9,300 infections and 600 deaths each year. To date, CRE infections occur mostly among patients in hospitals and nursing homes; people on breathing machines or with tubing inserted into their veins or bladders are at higher risk, as are people taking long courses of certain antibiotics. But newer, more resistant kinds of CRE seem to be causing more problems outside hospitals, in communities and among healthier people.

Tom Frieden, head of the CDC, refers to CRE as "nightmare bacteria." Why nightmarish? Because CRE carry genes rendering them resistant to multiple antibiotics—not only to carbapenems, which have been a "last resort" treatment for these kind of infections—but also to other broad spectrum antibiotics, like cephalosporins. CRE have been found on farms before. Monday's report stands out because the carbapenem resistance gene, called bla IMP-27, found on these farms is carried by a plasmid.

Plasmids are strands of DNA that can move easily from one bacterium to another, including across species. After acquiring the right kind of plasmid, with resistance to eight or ten or twelve different antibiotics, a bacterium on a farm or in the human gut could transform from something pretty benign to something lethal in an instant. Previous isolates of CRE found outside of hospitals have been less alarming, because they haven't carried this transmittable plasmid. Earlier this year, scientists also discovered transmissible (plasmid-carried) resistance to colistin—another antibiotic of last resort—in E. coli bacteria isolated from two U.S. pigs.

What happens when—when, not if—the same plasmid collects resistance genes to both colistin and carbapenems? That's the Nightmare on Main Street scenario that many experts fear and perhaps even expect in our future. Infections caused by gram negative bacteria carrying that super-plasmid would be virtually untreatable. As it spreads into the human population, one could reasonably expect a big increase in costs, hospitalizations and deaths.

To some degree, the genie is out of the bottle. By that I mean that farms, like hospitals, are now confirmed as reservoirs of resistance to last-resort drugs, like carbapenems and colistin. Focus now must be on how to change farm practice to try and limit the spread of those superbugs. That's a tall order when it comes to the U.S. pork industry, however.

Today's $22 billion U.S. pork industry may be the perfect storm when it comes to superbug creation. The industry concentrates huge amounts of pigs, manure and antibiotics on relatively few farms in a few counties in a few states. Only 21,687 farms specialize in hog production; they account for 90 percent of hog sales. Just three states, Iowa, North Carolina and Minnesota account for 55 percent of such sales. Routine use of antibiotics on such farms is common (although not carbapenems).

Day-old piglets routinely get injected with ceftiofur, which belongs to a critically important human class of antibiotics. Some piglets get multiple doses, increasing the pressure selecting for drug-resistant bacteria in those pigs and on their farms. What's less understood is that using one antibiotic in these settings increases resistance to all the antibiotics that have genes on the same plasmid. CRE bacteria with the bla IMP-27 gene carry resistance not only to carbapenems but also to cephalosporins like ceftiofur. So continuing to use ceftiofur and other antibiotics in weaner pigs likely is a big part of the problem.

Sticking one's head in the sand no longer seems like a viable strategy for the U.S. pork industry. Superbug genes are here and they're on our pig farms. The future's never going to be the same.

David Wallinga, MD, is the senior health officer at the Natural Resources Defense Council.

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