Antibiotic Use in Food Animals

Key reasons for this concern and confusion can be traced to numerous factors including:

• Antibiotic use in food animals is not a black-and-white issue. It is a complex issue that is all too frequently over simplified by both critics and proponents.
• Misunderstanding that a concern is not equivalent to risk.
• The disconnect between consumers and agriculture (and those in agriculture), with most consumers being at least three generations removed from the farm.
• Activist messaging, the media and the Internet are often inaccurate and misleading regarding antibiotic use, and in particular antibiotic resistance and its relationship to use, in food-animal production.

Antibiotic use in food animals is highly regulated by the U.S. Food and Drug Administration Center for Veterinary Medicine (FDA CVM). Regulatory oversight provides assurance in the development of safe products. Education and training encourages producers to have a strong relationship with their veterinarians and provides guidance on the responsible use of antibiotics. Government surveillance and testing ensures that no harmful residues, as established by the FDA, enter the food supply.

The use of antibiotics in food-animal production has elicited concern about antimicrobial resistance (AMR). The development and dissemination of antibiotic resistance is a highly complex, multi-faceted issue.

Figure 1

Resistance to antimicrobials continues to evolve, with many types of resistance mechanisms. As such, it is imperative that antibiotics be used appropriately not only in animal agriculture but also in the human population.

The issue of AMR is not strictly an issue of science-based decision-making. Like many other aspects of food production, the issue of AMR inherently invokes differing opinions, and, given the intricacies and size of the modern food production system, it’s a foregone conclusion that any policy issue will invoke many different perspectives. The symposium was intentionally designed to be respectful of all opinions, including the varying politics and values related to modern food production practices. Therefore, it is essential to initiate broad dialogue around the role of antibiotics in animal agriculture and the issue of antibiotic resistance.

Ultimately, key questions concerning antimicrobial use in human and animal populations revolve around:

• Who should benefit and by how much?
• What is “over” or “unacceptable” use?
• What is acceptable risk?

Given these questions, concern about AMR bacteria is not equivalent to risk. Risk to humans exists only if there is a causal pathway from the AMR bacteria in food-producing animals and humans. Risk is not a result of the hazard alone, but also in conjunction with the exposure (or dose).

Estimated farm-to-fork risk from on-farm antibiotic use is extremely low. In fact, the alternative risk of sub-optimal animal health may be higher than the risk of on-farm antibiotic use.

Although activists often claim that antibiotics used in livestock and poultry are the cause of human antibiotic resistance, the attributable risk of human disease outcomes, e.g., additional illness days due to resistance, associated with the use of antibiotics in food-producing animals is unknown, and studies show it is extremely low.

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is a new and potential health concern for persons in the swine/livestock industries, but current evidence indicates it is not a concern for the broader community as it has not been shown to be a significant cause of the overall MRSA burden in humans. Since LA-MRSA is not a food-borne pathogen, it is not a food safety or public health concern.

Common on-farm practices that consumers should know about regarding food-animal production include:

1. Modern livestock farms increasingly involve licensed veterinarians who advise on health management decisions.
2. Vaccines are used to protect animals from various illnesses.
3. Sick animals are treated with medicines, such as antibiotics, to restore their health, and protections are in place to ensure that their meat or milk is safe for people.
4. The FDA approves the use of all new animal drugs after testing and confirming animal safety and human food safety.
5. If antibiotics are administered to cure a sick animal, the animal itself — in the case of meat production — or animal products — such as milk — are not allowed to enter the food supply until the withdrawal period has passed and the medicine has sufficiently cleared the animal’s system. The required periods for withdrawing medication are specific for each drug and species and are approved by the FDA based on research studies of residues in edible tissues.

Animal agriculture stands on the belief that healthy animals make safe food. Those who produce food animals agree with the veterinarian’s oath: “Being admitted to the profession of veterinary medicine, I solemnly swear to use my scientific knowledge and skills for the benefit of society through the protection of animal health and welfare, the prevention and relief of animal suffering, the conservation of animal resources, the promotion of public health, and the advancement of medical knowledge.” Today, however, consumer concerns may cause two phrases in the oath to collide: “prevention and relief of animal suffering,” and “promotion of public health.”

Individuals dedicated to food-animal production recognize that proper production practices, such as maintaining flock and herd health by preventing disease through biosecurity and the use of vaccines, help minimize the need for antimicrobial use. Medically important antibiotics used in food-animal agriculture should be used under the supervision of a veterinarian to combat disease on a case by case basis. Access to antibiotics to prevent and treat animal disease is essential for the health of food animals as well as to ensure a safe food supply.

It is critical that policy actions regarding the use, limited use, or non-use of antibiotics in food-animal production be based on science with a commitment to carefully weighing the benefits and costs as well as the desired — and potentially undesired — consequences of any specific course of action.

In final analysis, the ultimate priority about antibiotic use going forward is the development of well-established, science-based criterion in the regulatory decision-making process. Simultaneously, the livestock industry should remain focused on continual improvement of good animal husbandry practices and disease prevention.

There should be an achievable, unified goal of “One Health: Healthy People, Healthy Animals, Healthy Food.”

January 2012