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Food Safety and Inspection
Service United States Department of Agriculture Washington, D.C. 20250-3700 |
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Food Safety and Inspection
Service United States Department of Agriculture Washington, D.C. 20250-3700 |
Office of the Under Secretary for Food Safety
U.S. Department of Agriculture
Remarks prepared for delivery by Dr. Catherine Woteki, Under Secretary for Food Safety, before the conference on Antimicrobial Resistance sponsored by the Royal Society of Medicine Foundation, the Royal Society of Medicine, and the Tufts University School of Medicine, May 4, 2000, Washington, DC.
It’s a pleasure to be here today to talk about antimicrobial resistance from the perspective of the U.S. Department of Agriculture (USDA). With the tremendous growth in international trade of agricultural commodities we have seen in recent decades, food safety issues must be addressed on a global level. Antibiotic resistance is no exception, so I am pleased to see this issue being addressed in an international forum. Antimicrobial resistance is a growing public health threat that has been identified as a major priority in the United States by a number of expert groups, including the Institute of Medicine, the American Society for Microbiology, and the Congressional Office of Technology Assessment. It also is a concern for our agricultural producers who are striving to produce safe, high-quality products.
A Complex Problem
Antibiotic resistance is a complex problem--one that requires attention by many diverse interests, including agriculture experts, public health experts, and regulatory agencies. The list of speakers at this conference certainly reflects the diversity of involvement needed to contain the problem of antimicrobial resistance. Here in the United States, the Department of Health and Human Services is leading the development of a coordinated public health action plan to address antimicrobial resistance, and I expect the action plan to be released shortly. USDA has participated in this effort through the Antimicrobial Resistance Working Group, which has membership from six USDA agencies.
The complexity of the antimicrobial resistance issue stems from the fact that two previously parallel stories are now converging. First is the story of how the inappropriate use of antibiotics in human medicine has contributed to the growing human health problem of antimicrobial resistance. The second story is the use of antibiotics in animal agriculture, and the growing recognition that this practice contributes to antimicrobial resistance in both animal and human pathogens.
We have long recognized that the health of food-producing animals is intrinsically linked to human health. But in the past, agriculturists resisted the idea that the use of antibiotics in animals could relate to resistant pathogens in humans. It's time to move beyond that, because there are now cases that provide evidence of such a link. For example, a May 1999 article in the New England Journal of Medicine showed a genetic association between resistant Campylobacter strains from chicken products produced and consumed in Minnesota and resistant Campylobacter strains causing infections in Minnesota residents.
In addition, a report published by the Institute of Medicine in July 1998 acknowledged that there is a link between the use of antibiotics in food animals and the development of bacterial resistance to these drugs.
I want to acknowledge from the outset the multifactorial nature of drug resistant human infections. As Under Secretary for Food Safety for USDA, I am here to focus on those infections that may be acquired through the food supply. It is well known, however, that resistant human infections are acquired in other ways, such as through the use or abuse of antimicrobials in human medicine.
It is not possible to quantify the contribution of antibiotic use in the agricultural setting to the broader problem of drug resistance in humans, nor do I believe that this exercise would be particularly helpful. I believe it is more helpful to acknowledge that antibiotic use in animals contributes to the problem and that prudent antibiotic use should be encouraged in all sectors. The agricultural community must accept part of the responsibility.
Both of these pathways to antimicrobial resistance—human and animal—must be managed. The emphasis is on the word managed, because, a totally risk-free system of food production is an unreasonable and unattainable goal. At least so far, microbes always develop resistance to antimicrobials used against them. But we can intelligently manage the use of antimicrobials so we can prolong their usefulness for both humans and animals.
Risk Assessment
The need to take action now to address the problem of antimicrobial resistance in our animal populations does not mean we have all of the answers to our questions. Many data gaps remain. For example, we do not know what degree of resistance is transferred for various organisms. In many cases, we do not even know exactly how resistance is transferred. We also do not know which practices related to antibiotic use present the greatest risks.
But having to make food safety decisions and take action based on incomplete data is nothing new to risk managers. We must make the best possible public health decisions based on the information available today, and build our knowledge base so that we can make more informed decisions in the future.
Sound science is the key in making these decisions. In January 1999, the Food and Drug Administration published a discussion paper—commonly referred to as the "Framework document," that presents a risk-based process for evaluating the microbial safety of antimicrobial drugs used in food producing animals. FDA Commissioner Dr. Jane Henney will be here tomorrow to provide more detail on this document and the risk assessment models FDA is developing to account for the transfer of resistance from bacteria in food producing animals to bacteria in humans via food. The United States firmly believes that such a scientifically sound, risk-based approach is key to the decisionmaking process for the use of antimicrobials in food producing animals—both here and abroad.
USDA’s Current Role in Managing Antimicrobial Resistance
Because I am here to address the agricultural sector, let me provide a very brief overview of the role of veterinary drugs in food animal production and then discuss what USDA is currently doing to address the problem of antimicrobial resistance.
Veterinary drugs are a critical component of food animal production and contribute to the exceptionally high level of health we find in food animals today. They also provide other benefits related to animal welfare and economic return for the industry. Since the benefits of antibiotics in enhancing growth and feed efficiency in animals were observed almost half a century ago, the number and use of these products has increased.
U.S. controls regarding the use of veterinary drugs emphasize sound science and risk assessment. And in addition to activities that generally address the proper use of these drugs, Federal agencies also have in place programs to learn more about, track, and reduce antimicrobial resistance in animals. Many of these activities are joint activities among several Federal agencies and are supported by the agricultural industries.
First is surveillance. In 1996, HHS and USDA established the National Antimicrobial Resistance Monitoring System for Enteric Bacteria—NARMS-EB. The goal of the system is to obtain a spectrum of, and monitor trends in, antimicrobial resistance in foodborne pathogens. NARMS collects and analyzes Salmonella, Campylobacter, E. coli and enterococcus isolates from animals and humans. USDA supports the project through three of its agencies. The Food Safety and Inspection Service (FSIS) contributes isolates from its regulatory program for Salmonella and isolates of Campylobacter from its microbiological baseline data collection surveys. The Animal and Plant Health Inspection Service (APHIS) contributes isolates from clinically ill animals and isolates from healthy animals on farms. And the Agricultural Research Service (ARS) conducts all testing and analysis of data.
APHIS also carries out farm surveys through the National Animal Health Monitoring System (NAHMS), which provide information on the spectrum of antimicrobial resistance and the relative contribution of various management practices to the development of resistance.
In addition to surveillance, USDA carries out research on antimicrobial resistance. Research has a vital role in delaying and controlling the emergence of resistance in pathogens associated with food products because our progress is hampered by data gaps. We need basic as well as applied research on antimicrobial resistance. More research is needed to assess which agricultural practices can reduce antimicrobial use, to identify what types of antimicrobial use present a high risk of resistance, and to better understand how resistance is transferred by means other than food.
For example, the Institute of Medicine, in its 1998 report, indicated that farm workers could be at greater risk for clinical antimicrobial resistance, so environmental factors may also play a role in this transfer. A recent article in the April 27th New England Journal of Medicine provides further evidence of an environmental link. The authors concluded that a boy’s infection by Salmonella enterica serotype typhimurium resistant to ceftriaxone—a widely used pediatric antibiotic—came from cattle on his farm.
USDA’s Agricultural Research Service recently established an Antimicrobial Resistance research unit in Athens, GA. Researchers there are determining how both pathogens and nonpathogens acquire and transfer antibiotic resistance and whether the presence of resistance alters virulence in pathogens. A major accomplishment has been the development of a rapid gene probe for Salmonella typhimurium DT-104—a multi-drug resistant pathogen that is difficult and time-consuming to identify.
In addition, USDA’s Cooperative State Research, Education and Extension Service (CSREES) last year awarded three grants through a new program within the National Research Initiative that specifically address antimicrobial resistance. These studies seek to understand the processes involved in the rapid spread of multiple drug resistance in poultry and to identify management practices that may help to address the problem of antimicrobial resistance in cattle.
Prevention and control is a third area of emphasis within USDA. This is closely related to the research area, because as scientists determine what on-farm interventions can help to reduce antimicrobial resistance in animals, these management practices can be encouraged. For example, the use of vaccines to eliminate pathogenic bacteria from the food chain is a relatively unexplored area. And competitive exclusion cultures are providing alternatives to antimicrobial use in animals.
There are some management practices that producers can take now to prevent and control resistance. They include improved nutrition for farm animals, biosecurity measures to minimize the introduction of infections on the farm, and, of course, the prudent use of antimicrobials. All of these steps are supported by USDA.
These activities—surveillance, research, and prevention and control—are part of a multi-hurdle approach within USDA. Each by itself will not solve the problem, but together, they provide cumulative protection against antimicrobial resistance. Through the action plan now being developed by Federal agencies, these public health protections will become even stronger.
Another way USDA is helping to reduce antimicrobial resistance is through its successful strategy to reduce pathogen loads on meat and poultry products. Through mandatory HACCP and Salmonella performance standards for meat and poultry products, USDA has seen significant reductions in Salmonella levels in most types of products. Reduced levels of Salmonella are not a solution to the problem or a substitute for other efforts, but any action USDA takes to reduce pathogen loads on meat and poultry will help to reduce the transfer of resistant pathogens to humans.
Future Directions--Public Health Action Plan
For the future, as I mentioned, the U.S. agencies with a role in managing the problem of antimicrobial resistance, including USDA, are developing a public health action plan through an interagency Task Force on Antimicrobial Resistance that was created in 1999. The task force is co-chaired by the Centers for Disease Control and Prevention, the Food and Drug Administration, and the National Institutes of Health. It also includes the Agency for Health Care Research and Quality, the Department of Defense, the Department of Veterans Affairs, the Environmental Protection Agency, the Health Care Financing Administration, and the Health Resources and Services Administration. This extensive list reflects the fact that antimicrobial resistance is a multifaceted problem, and combating it successfully will require creative solutions on many fronts.
The plan reflects a broad-based consensus of Federal agencies on actions needed to address antimicrobial resistance. It is being developed through a public process, and a public meeting was held last July in Atlanta. The purpose of the meeting was to solicit ideas from a variety of constituents about possible ways that Federal agencies might address antimicrobial issues. We have received input from state and local government agencies, universities, professional societies, pharmaceutical companies, health care delivery organizations, agricultural producers, consumer groups, and other members of the public. Ideas discussed at the July public meeting have been incorporated into the action plan. When it is ready, the action plan will be made available to the public through the Federal Register, with opportunity for additional public input.
I can’t provide details at this time, but I can tell you that the plan will have four areas of focus—surveillance, prevention and control, research, and product development. Under the proposed action plan, many of the activities already underway to address antimicrobial resistance will be expanded, and new activities will be initiated. All four areas will be important to containing the problem of antimicrobial resistance, and it will take involvement from all of the constituents I mentioned to implement the action plan.
Closing
In closing, I believe that the next few years hold much promise in terms of addressing the growing issue of antimicrobial resistance. The development of a multi-agency, coordinated action plan in the United States is a major step forward. The United States looks forward to a continuing dialog on antimicrobial resistance not only domestically, but internationally as well.
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For Further Information:
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