June 2010 Issue

Antibiotics in Animal Agriculcuture — Experts Weigh in on a Meaty Issue
By Sharon Palmer, RD
Today’s Dietitian
Vol. 12 No. 6 P. 32

Does the nontherapeutic use of these drugs in livestock help spread resistant bacteria or ensure a safer food supply? Today’s Dietitian listens in on the conversation.

Healthcare professionals know how critical the issue of antibiotic resistance—a microorganism’s ability to withstand the effects of antibiotics—is to patient care. The widespread use of antibiotics is commonly blamed for the rise in resistant bacteria. But have you ever made the connection between antibiotic resistance and the way our food system currently produces meat?

Organizations such as the Union of Concerned Scientists point out that the vast majority of antibiotics sold in the United States are used for food animals, mostly in tiny doses to promote weight gain or more efficient feed consumption. Industrialized food systems that produce poultry, pork, beef, and farmed fish routinely use antibiotics nontherapeutically, leading to increased antibiotic resistance among bacteria that cause human infections, according to the healthcare coalition Health Care Without Harm. The conversation on antibiotic overuse in animals has even gone mainstream; it was the subject of a February CBS television news investigation by Katie Couric.

“We’re rapidly increasing the infections that we can’t treat with antibiotics. The overuse of antibiotics is helping to spawn new strains of bacteria resistant to all antibiotics,” says David Wallinga, MD, MPA, director of the food and health program at the Minneapolis-based Institute for Agriculture and Trade Policy. “It’s been estimated that over 80% of all antimicrobials in America are used in animal agriculture. Most antibiotics are added to animal feed for healthy animals, such as in pigs, poultry, and beef cattle. Their purpose is not to treat diseases but to make animals bigger faster so that they can go to market more quickly and to dose them with antibiotics before they get sick because of the way they are being raised.”

Tune in to the current research on antibiotic resistance and animal agriculture, learn about alternate ways to raise livestock and the movements to restrict nontherapeutic antibiotic use, and understand why dietitians should join the debate.

Antibiotic Resistance on the Farm
How do antibiotics used for animals eventually lead to antibiotic resistance? Scientists know that bacteria become resistant to antibiotics through overexposure; tough bacteria strains survive the exposure and then pass on the resistance trait to the next generation. Thus, the antibiotic destroys all of the vulnerable bacteria, leaving only the resistant bacteria to survive. In the end, the antibiotic is no longer effective.

While the first line for prevention of antibiotic resistance in humans is controlling the number of prescriptions and ensuring that patients take the whole series of antibiotics they are given, many experts believe the common practice of administering antibiotics to food animals contributes to the problem. Many antibiotics used legally and routinely in animal agriculture are identical (or nearly so) to human medicines such as those containing penicillin, tetracycline, erythromycin, and sulfa.

Wallinga explains that it’s not so much a problem of antibiotic residues getting into the meat. “Rather, the problem is that using antibiotics in food animals helps spread resistant bacteria, including in meat from those animals. Studies also show that antibiotics in animal feed can lead to antibiotics and antibiotic-resistant bacteria in airborne dust blowing off of farms. This poses resistance risks to workers, to farm families, and to the community. When antibiotics are used in animal feedlots, it also can spread resistance into groundwater. Antibiotics get into the manure and the soil, which creates antibiotic-resistant bacteria,” he notes.

Several studies have investigated the relationship between antibiotic resistance and animal agriculture. In December 2007, the USDA issued an information sheet on concerns for animal and human health related to methicillin-resistant Staphylococcus aureas (MRSA), reporting that the evolution of MRSA and other drug-resistant pathogens have been linked to extensive antibiotic use in medicine and food animal production. A 2003 Institute of Medicine/National Academy of Sciences report concluded that antimicrobial use in human medicine alone will have little effect on the current antibiotic-resistant situation and that substantial efforts must be made to decrease inappropriate overuse of antibiotics in animals and agriculture.

A report published in the June 2002 issue of Clinical Infectious Diseases based on a two-year review by experts in human and veterinary medicine, public health, microbiology, biostatistics, and risk analysis of more than 500 scientific studies on the human health impacts of antimicrobial use in agriculture recommended that antimicrobial agents no longer be used in agriculture in the absence of disease; instead, their use should be limited to therapy for diseased individual animals and prophylaxis when disease is documented in a herd or flock. An April 1999 study by the General Accountability Office concluded that resistant strains of three microorganisms that cause food-borne illness or disease in humans—Salmonella, Campylobacter, and E. coli—are linked to antibiotic use in animals.

The World Health Organization has urged for an end to the nontherapeutic use of drugs used to treat human disease or that are related to such medicines in animals. The U.S. Interagency Task Force on Antimicrobial Resistance was formed in 1999, cochaired by the FDA, the Centers for Disease Control and Prevention, and the National Institutes of Health, and includes the Agency for Healthcare Research and Quality, the Centers for Medicare & Medicaid Services, the Health Resources and Services Administration, the USDA, the Department of Defense, the VA, and the Environmental Protection Agency. The group developed a plan that outlines the judicious use of antibiotics in animals, including recommendations for phasing out the use of antibiotics in animals for growth promotion or feed efficiency.

In testimony to Congress in July 2009, FDA Principal Deputy Commissioner Joshua M. Sharfstein, MD, said, “Antimicrobial use in animals has been shown to contribute to the emergence of resistant microorganisms that can infect people.”

An Alternative Way to Raise Animals
If you’ve seen the movie Food, Inc, then you know all about the movement to raise animals in a more humane way that doesn’t require the nontherapeutic use of antibiotics. Instead of crowding livestock into a confined animal feeding operation, many farmers are returning farm animals to the pasture and, therefore, discontinuing the need for nontherapeutic antibiotics.

Ashley Colpaart, RD, LD, chair of the Hunger and Environmental Nutrition (HEN) Public Policy Committee, explains that it’s the confined animal feeding operation setting that creates the dependence on nontherapeutic antibiotics. “In the current agricultural system, animals grow large in a short period of time, and they are in conditions in which they get sick more easily. Thirty thousand chickens can be in one dark house, where the birds sit in pounds of feces and the air is thick with ammonia. It’s like a machine, not a farm,” says Colpaart.

“The large issue over antibiotics in animals is because they are used as prevention because of the way animals are concentrated on feedlots. There is more stress on their bodies and they are more prone to disease. If you’re going to change this, you have to give animals more space,” adds Holly Freishtat, CN, MS, a sustainable food specialist at Cultivate Health.

The Center for Science in the Public Interest developed an antibiotic resistance project because of antibiotic overuse, reporting that the United States lags behind many other countries in protecting its citizens from antibiotic resistance due to the antibiotic use in livestock. “There are plenty of ways to raise animals without routine use of antibiotics. Europe doesn’t use antibiotics in this way,” says Wallinga, who notes that Denmark moved to preserve antibiotics from routine animal use without experiencing major difficulties in changing farming practices. “It’s doable, and we need to do it.”

PAMTA to the Rescue
Rescuing antibiotics from overuse is the mission of the Preservation of Antibiotics for Medical Treatment Act of 2009, referred to as PAMTA, which has been reintroduced into legislation with an outpouring of support from the health and medical community. A veritable who’s who of health organizations have signed on to support PAMTA, including the American Public Health Association, the American Medical Association, the American Nurses Association, the American Academy of Pediatrics, and about 300 other reputable organizations. Colpaart says this bill has been introduced in the last three legislative sessions but has now gained more traction because of the availability of more scientific research, backing from reputable organizations, and changes at the USDA.

If enacted, PAMTA would require the FDA to review the approvals it previously issued for animal feed uses of the seven classes of antibiotics that are important to human medicine. Any found to be unsafe regarding potential resistance would have its approval rescinded. In addition, the Health Care Practitioner Petition is circulating, allowing individual practitioners, including RDs, to advocate for the act.

Resisting PAMTA
Not everyone agrees that the livestock industry needs to change its antibiotic practices. The cattle, pork, and poultry industries argue that using FDA-approved antibiotics helps them ensure animals’ health and resource efficiency and that there is no conclusive scientific evidence that the use of antibiotics on farms contributes significantly to increased antibiotic resistance in humans.

The American Veterinary Medical Association also opposes PAMTA, reporting that it shares the concerns of the human medical community, the public health community, governmental agencies, and the public regarding the potential problem of resistance developing in animals and then being transferred to humans. But it believes these medicines are important to prevent and treat ailments before disease-causing bacteria enter our food supply, and passing legislation that would ban the use of these antibiotics before science-based studies and risk-based evaluations are conducted to determine whether there is an actual risk to human health would be detrimental to animal and human health.

“PAMTA would disallow important antimicrobials from being used in water or feed for growth promotion/feed efficiency [and] prevention and potentially control of animal diseases. In addition to providing a safe, healthy food supply, the ability to prevent and control diseases is especially critical to maintaining animal health and well-being,” says Christine Hoang, DVM, MPH, CPH, assistant director of the scientific activities division of the American Veterinary Medicine Association. “In the veterinary community, we recognize that some of the products that are labeled for growth promotion also have therapeutic effects in preventing disease and that there are some that do not have any impact on the development of resistance in humans. In such cases where a ban would diminish our ability to promote animal health and well-being and provide a safe, healthy food source, that would be problematic for all of us.”

Dollars and Sense
Perhaps the biggest stumbling block to curtailing antibiotic use in animals boils down to money. The meat industry worries that a change in antibiotic policy would increase the cost of producing meat, which would be passed down to buyers.

But some experts believe the cost of reducing antibiotic use may not be so bad after all. The National Research Council estimates that a ban on nontherapeutic antibiotic use would increase per capita costs by about $5 to $10 per year. In addition, adopting other methods of maintaining animal health, such as reducing overcrowding, controlling heat stress, vaccinating, and using beneficial microbial cultures, could reduce drug use and thus cut costs. Freishtat says, “The costs to reduce antibiotic use are affordable. In Denmark, the cost increase was not exorbitant; it was only a little more expensive. If we just changed the way we raise livestock slightly, we can raise healthy animals that aren’t prone to disease. If you increase the price of meat, there are trade-offs with public health. We need to address the public health issue that we shouldn’t be eating meat three times a day.”

There’s also the public health price tag for antibiotic resistance. Experts at Tufts University estimate that antibiotic-resistant infections cost the U.S. healthcare system $50 billion per year.

“Antibiotic resistance is very costly. More resistant bugs means both that more people will get sick and also that people coming down with resistant infections will be sicker. There is a shift in our society. We used to use generic antibiotics such as penicillin and tetracycline that worked well for most things. Now these antibiotics no longer work well, and you have to use much more expensive antibiotics,” says Wallinga.

Dietitians Enter the Conversation
How does the debate over antibiotics in livestock affect dietitians? Stacia Clinton, RD, LDN, New England Healthy Food in Health Care associate at Health Care Without Harm, believes there’s an important connection between dietetics practice and preserving antibiotics. She points out that the traditional dietetics curriculum tends to leave out an important segment of education: agriculture and where food actually comes from, a key component of healthy food for healthy people.

“Tremendous strides have been made to educate dietitians and other nutrition professionals in the area of food systems from field to plate,” says Clinton. “RDs have engaged around this issue. They have made their presence known by signing the Health Care Practitioner Petition. They are quick to support the cause due to their own interactions with antibiotic resistance with their work settings. By taking action to support PAMTA, dietitians will be empowered to be leaders in supporting a healthful and safe food supply. The overuse of antibiotics creates a food supply that can be dangerous to populations, especially those that are the most vulnerable: children, the elderly, and people with a compromised immune system. By not fighting to protect the effectiveness of antibiotics, dietitians are, in essence, shifting their role from a curative one as part of a healthcare team to a palliative one merely managing the dramatic side effects of repetitive doses of ineffective antibiotic treatment.”

Health Care Without Harm has been a key supporter of saving antibiotics for human use. This past fall, it launched the Balanced Menus Challenge, a voluntary commitment for hospitals to reduce meat procurement by 20% in one year as part of a climate change mitigation strategy and a way to reduce the nontherapeutic use of antibiotics in meats. According to Freishtat, 29 hospitals already have taken this challenge. She encourages hospital foodservice departments to utilize the Balanced Menus tool kit for information to help support sustainably produced meat in the hospital setting.

Noticeably absent on the list of organizations supporting PAMTA is the American Dietetic Association (ADA). The HEN Public Policy Committee considers preserving antibiotics a key issue and has utilized publications, listservs, and e-newsletters to engage membership to support this movement. HEN Public Policy Committee members contacted the ADA’s Legislative and Public Policy Committee to enlist its support for PAMTA. The committee reviewed information from HEN and PAMTA and reported that the effects of the nontherapeutic use of antibiotics in livestock on the environment and public health is a complex issue that deserves comprehensive and careful consideration, especially when there is a lack of consensus on the data within the scientific community. The committee concluded that it is outside of its scope to indirectly take a position or stance by supporting or opposing PAMTA on behalf of the organization and all of its members.

According to ADA President Jessie M. Pavlinac, MS, RD, “ADA is certainly not opposed to PAMTA. ADA’s Legislative and Public Policy Committee has reviewed the PAMTA legislation and has conducted a review of the medical use of antibiotics in humans and the use of antibiotics in animals for food. Since ADA has not developed an official evidence-based position on the use of antibiotics in the food supply and the issue is not addressed in ADA’s existing position on food safety, the committee has chosen to not support PAMTA at this time. However, ADA does not oppose PAMTA and individual members are free to support or oppose PAMTA as they choose.”

A public policy blog titled “Why won’t ADA support PAMTA?” has received a number of recent responses urging the ADA to consider supporting PAMTA. On April 9, Pavlinac said on the blog, “Thank you for your comments. I am going to look into this and will follow up.” Since then, she has reported that, at the Legislative and Public Policy Committee’s suggestion, the ADA will convene a small workgroup comprised of members from that committee and the ADA to further address PAMTA.

Dietitians continue to speak out on the use of antibiotics for farm animals in blogs and listserv discussions. While the future for antibiotics in animal agriculture is uncertain, one thing seems sure: The conversation is loud and dietitians are raising their voices to be heard.

— Sharon Palmer, RD, is a contributing editor at Today’s Dietitian and a freelance food and nutrition writer in southern California.

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