The veterinary landscape for the production of food animals is changing with the Food and Drug Administration's (FDA) Veterinary Feed Directive, but, even as the use of antimicrobials in food-producing animals comes under direct veterinary supervision, important scientific and ethical insights to drive future policy to reduce antimicrobial resistance are missing.
Mike Apley, veterinarian and professor at Kansas State University, speaking at the National Institute of Animal Agriculture (NIAA) Antibiotics Symposium, identified policy issues involving antibiotic use in the production of beef, pork or poultry that cannot easily be resolved either by the science of pharmacology or by ethical principles alone.
“In my opinion, antimicrobial-use monitoring should be actual use tied to reason for use.”
The mere enforcement of labeled usage or the reduction of total kilograms of antibiotics may not be the most effective approaches to reducing antimicrobial resistance, according to the professor of production medicine and clinical pharmacology.
What’s more, stakeholders and regulators must find a way to move forward with antimicrobial-use policy when data is incomplete, and even where it exists, it is not interpreted in the same way by different stakeholders.
There is a range in society’s acceptance of ideas about the use of antibiotics in food-producing animals from popular to sensible to radical to unthinkable.
Veterinary responsibility for antibiotics usage
“Going forward, the emphasis on treatment records will be greater than it has ever been,” Apley said.
The veterinarian is going to be responsible for all medically important antimicrobial uses in food production animals, he said, and this brings significant change in protocols, treatment records and reporting for meat and poultry production:
- The days of verbal treatment protocols are gone
- The days of unacceptable treatment records are gone
- The days of nontransparent use of antimicrobials in food animals are coming to an end
He said that not only is more and better data about antibiotics usage in food animal production needed, but the only way to get it is to “give agriculture the steering wheel for data collection” while providing government audit of the sampling strategy and data collection.
Apley offered the following recommendations for obtaining “the needed granularity in the data”:
- Give agriculture the steering wheel for data collection
- Government audit of the sampling strategy and data handling
- Absolute guarantee of anonymity for participants
- Sampling structure must balance a view of the industry with utility for individual participants
Limitations of metrics on antibiotic usage
“Antibiotics sales data do not drive accurate estimates of indications for use, or even actual use,” Apley said.
“In my opinion, antimicrobial-use monitoring should be actual use tied to reason for use. [Collecting data about] total kilograms [of antimicrobials] as a metric only serves as a stick to drive ‘cut the use’ as a goal. Animal daily doses (ADD) and animal regimens (AR) provide a look into drug exposure as well as numbers of animals receiving the regimen. There may be different regimens for the same drug in a species,” he added.
“Only actual use tied to reason for use will allow us to drive antimicrobial stewardship in food animals,” he reiterated.
Bringing "true knowledge" to bear on antibiotics usage
Even with more and better data likely to be available in the future, the best policy to avoid antimicrobial resistance cannot be expected to be clear-cut. He indicated that bringing “true knowledge” to bear on public policy and clinical practices remains a challenge.
Apley pointed to examples in human and veterinary medicine where current scientific understanding falls short in providing clear direction for determining basics such as dosing and duration of antibiotic therapy.
“Bringing ‘true knowledge’ to bear on public policy and clinical practice remains a challenge.”
For example, Apley challenged listeners – who, in addition to other veterinarians, included policymakers from FDA and Centers for Disease Control (CDC), experts in human medicine and consumer group activists: “Who decided that the exposure dynamics for growth promotion (low and long) are the most likely to select for resistant organisms?
“Don’t confuse a policy decision to reduce total kilograms of drug with proof that this exposure is the worst exposure to select for resistant organisms.
“It’s time to wake up!” he challenged the meeting’s attendees. “The pharmacokinetics and pharmacodynamics for efficacy don’t necessarily match with optimal exposure for minimizing the selection for resistant organisms,” he said.
Suggesting that recommendations on antibiotic labeling may not reflect the best pharmacokinetics for efficacy and avoidance of antimicrobial resistance, Apley said, “We have focused on dose comparisons for the same duration in veterinary and human medicine.” And in human medicine, he continued, patients are directed, “Take your antibiotics for as long as your doctor prescribes so that you don’t get a relapse with a resistant infection.”
“Labeled use doesn’t necessarily mean judicious use,” he said. “It is not necessarily compatible with stewardship. Labeled use is not necessarily the regimen most likely to minimize selection for resistant organisms.”
“Don’t confuse a policy decision to reduce total kilograms of drug with proof that this exposure is the worst exposure to select for resistant organisms.”
Debate about antibiotics in food animals
Beef, pork and poultry producers and their veterinarians, Apley said, need to be actively engaged in the debate that will frame antimicrobial usage for the future.
It is a debate that will determine how society weighs incomplete and sometimes contradictory data and resolves conflicting values. It involves policy issues that cannot be resolved on the basis of science or ethical principles alone.
“We are going to have to figure out how to move forward without a clearly defined smoking gun or the lack of a smoking gun. And what we get to there is really a discussion of where lies the burden of proof. Does someone have to prove that it does cause a problem? Or does someone have to prove that it doesn’t?” he said.
Stewardship is a commitment to a decision-making cycle in which the veterinarian is continually engaged.