Antimicrobial Stewardship: A Need for International Standards

The following commentary does not necessarily reflect the views of AgWeb or Farm Journal. The opinions expressed below are the author's own.

Like other pathogens and agricultural pests, antibiotic-resistant bacteria do not recognize international borders. And while numerous countries move toward tighter regulations and more judicious use, inconsistencies in regulations and practices in other countries can increase the risk of multi-drug-resistant diseases spreading internationally.

Recognizing the potential for resistant pathogens developing within livestock production systems, the 181 member countries of the World Organization for Animal Health (OIE) have spent 10 years developing a comprehensive set of International Standards and guidelines for responsible and prudent use of antimicrobial products in animals and for the surveillance and monitoring for antimicrobial resistance.

Last week during its General Session, the OIE updated those standards while adopting some standardized definitions and language regarding antimicrobial use in livestock.

In updating its standards, the OIE lists veterinary and medical supervision of antimicrobial use in animals and humans as a high international priority. Toward that goal, they adopted definitions specifying veterinary-medical use versus non-veterinary-medical use of antimicrobials.

The OIE defines veterinary-medical use as the administration of an antimicrobial agent to an individual or a group of animals to treat, control or prevent infectious disease. The organization also adopted definitions for each category of use, similar to those employed in the United States:

• Treat: Administer an antimicrobial agent to an individual or a group of animals showing clinical signs of an infectious disease;
• Control: Administer an antimicrobial agent to a group of animals containing sick animals and healthy animals (presumed to be infected), to minimize or resolve clinical signs and to prevent further spread of the disease.
• Prevent: Administer an antimicrobial agent to an individual or a group of animals at risk of acquiring a specific infection or in a specific situation where infectious disease is likely to occur if the drug is not administered.

The OIE defines non-veterinary-medical use as “the administration of antimicrobial agents to animals for any purpose other than to treat, control or prevent infectious disease; it includes growth promotion, defined as the administration of antimicrobial agents to animals only to increase the rate of weight gain or the efficiency of feed utilization.” The updated guidelines specify that “responsible and prudent use of antimicrobial agents does not include the use of antimicrobial agents for growth promotion in the absence of risk analysis.” The guidelines also urge prohibition of growth-promotion uses of critically important classes of antibiotics used in human medicine, including Fluoroquinolones, Colistin and third and fourth generations of Cephalosporins.

In the United States, FDA’s Guidance for Industry 213 led to voluntary removal of performance or production claims from medically important antimicrobials. However, the OIE notes that 60 of its member countries continue to use antimicrobials for growth promotion, either with direct authorization or because of a lack of regulations.

While the long-term effects of judicious use guidelines on resistance trends remain unknown, most stakeholders agree that more veterinary oversight of antimicrobial use and phase-out of growth-promotion uses should serve as a positive step. Global adoption of those standards could help prevent emergence of multi-drug-resistant pathogens that humans, wildlife or livestock could carry across borders and into a herd near you.