Groups Provide New Guidance on Antimicrobials

AVMA believes antimicrobial stewardship can be achieved whether the intent is prevention, control, or treatment. ( Geni Wren )

The AVMA, Canadian VMA, and Federation of Veterinarians of Europe are calling for continuous monitoring of antimicrobial use and resistance at a global level. The AVMA also has created definitions of antimicrobial use for treatment, control, and prevention.

A new joint statement from the AVMA, CVMA, and FVE "describes broad steps and strategies veterinarians around the world can take to preserve the effectiveness and availability of antimicrobial drugs while safeguarding animal, public and environmental health," according to a Dec. 6 announcement. The AVMA Board of Directors adopted the joint statement and the AVMA definitions of antimicrobial use during a November 2018 meeting.

According to the introduction to the new definitions, "AVMA believes antimicrobial stewardship can be achieved whether the intent is prevention, control, or treatment, and attempts to prioritize antimicrobial stewardship by therapeutic purpose are misguided. Stewardship is better demonstrated by the clinical rationale for antimicrobial therapy."

Joint statement

The new joint statement on continuous monitoring follows up on a 2011 joint statement from the AVMA and FVE calling for responsible and judicious use of antimicrobials. The CVMA signed on to that statement in 2014.

"Antimicrobial resistance doesn't recognize borders, so efforts to combat antimicrobial resistance need to cross borders as well," said Dr. John de Jong, AVMA president, in the announcement about the new joint statement. "This joint statement is an important step in recognizing ways we can work together to prevent resistance and ensure that antimicrobials continue to be used judiciously in animals."

"As veterinarians, we oversee the appropriate and responsible use of antimicrobials in animals, thereby helping minimize the emergence and spread of antimicrobial resistance," said Dr. Terri Chotowetz, CVMA president, in the announcement. "By working together, we are demonstrating our professional responsibility in supporting the overarching international strategy on antimicrobial resistance and use."

The joint statement makes 14 recommendations, summarized here:

  • All countries should have a robust regulatory system for the authorization and manufacturing of medicinal products and a legislative system to regulate distribution and sales of these products.
  • Illegal manufacturing, distribution, or sales of medicines should be prosecuted.
  • Antimicrobials that are critically important in human medicine should only be administered to animals with the oversight of a veterinarian.
  • A robust global network of surveillance and monitoring systems for antimicrobial use and resistance development should be established.
  • Easily available, effective, rapid, and standardized diagnostic tests should be available in order to carry out susceptibility testing. Results of these tests should be made available to facilitate evidence-based decisions about antimicrobials.
  • Sufficient funding should be available for further research on and development of rapid and affordable diagnostic tests.
  • Harmonized standards for measuring, evaluating, and interpreting data on antimicrobial use and resistance need to be developed. The AVMA, CVMA, and FVE will support the work of the World Organisation for Animal Health (OIE) and European, Canadian, and U.S. agencies in this area.
  • Veterinarians must retain access to effective antimicrobials for therapeutic purposes for animals suffering from a bacterial disease.
  • Record keeping at the patient or practice level is essential for the evaluation of the success of antimicrobial treatments.
  • The AVMA, CVMA, and FVE will contact all organizations working to address antimicrobial resistance at a global level to ensure that the AVMA, CVMA, and FVE are always consulted.
  • The AVMA, CVMA, and FVE will call on their members, veterinary organizations, veterinarians, veterinary technicians, and animal keepers to contribute to the collection of data on antimicrobial use in animal health and on the occurrence and spread of antimicrobial resistance.
  • The AVMA, CVMA, and FVE will call on decision-makers to ensure that trade standards take into account the monitoring of antimicrobial use and resistance and the stewardship of antimicrobials.
  • The AVMA, CVMA, and FVE will collaborate in promoting responsible use of antimicrobials in animal production and animal care in all countries and particularly in the developing world.
  • The AVMA, CVMA, and FVE will continue to take a leadership role in promoting global antimicrobial stewardship.

Definitions

A lack of clear definitions has led to confusion about therapeutic intent in antimicrobial uses and about whether various uses comply with principles of antimicrobial stewardship, according to background materials from the AVMA Committee on Antimicrobials.

In 2017, the World Health Organization released the WHO Guidelines on Use of Medically Important Antimicrobials in Food-Producing Animals. According to the guidelines, "We recommend complete restriction of use of all classes of medically important antimicrobials in food-producing animals for prevention of infectious diseases that have not yet been clinically diagnosed."

A California law effective in 2018 says that antimicrobial stewardship includes a commitment "to use medically important antimicrobial drugs only when necessary to treat, control, and, in some cases, prevent, disease."

According to the AVMA Committee on Antimicrobials: "Antimicrobial stewardship cannot be ranked by intent of use for prevention, control, or treatment. Strategic uses of antimicrobials for the purposes of prevention, control, and treatment of disease may each meet the requirements of antimicrobial stewardship. Stewardship is better defined by decisions that influence the need for antimicrobial therapy in the first place and that maintain the effectiveness of antimicrobials when they are used."

Factors include the following:

  • Systems of husbandry that reduce the risk of disease.
  • Careful diagnostic evaluation.
  • Good decision-making to use or not use antimicrobials.
  • Prudent choice of drugs, dosage, and duration.
  • Records indicating appropriate follow-up and re-evaluation.

The AVMA Committee on Antimicrobials developed the definitions of antimicrobial use to minimize confusion regarding therapeutic intent in the context of individual animals or populations of animals (see sidebar).

Earlier in 2018, the AVMA House of Delegates adopted core principles of antimicrobial stewardship. See the AVMA policies on antimicrobials and other resources.

AVMA Definitions of Antimicrobial Use for Treatment, Control, and Prevention

AVMA believes antimicrobial stewardship can be achieved whether the intent is prevention, control, or treatment, and attempts to prioritize antimicrobial stewardship by therapeutic purpose are misguided. Stewardship is better demonstrated by the clinical rationale for antimicrobial therapy. We provide the following definitions for treatment, prevention, and control in the context of antimicrobial use in individual animals or populations of animals.

Antimicrobial prevention of disease (synonym: prophylaxis):

  1. Prevention is the administration of an antimicrobial to an individual animal to mitigate the risk for acquiring disease or infection that is anticipated based on history, clinical judgement, or epidemiological knowledge.
  2. On a population basis, prevention is the administration of an antimicrobial to a group of animals, none of which have evidence of disease or infection, when transmission of existing undiagnosed infections, or the introduction of pathogens, is anticipated based on history, clinical judgement or epidemiological knowledge.

Antimicrobial control of disease (synonym: metaphylaxis)

  • Control is the administration of an antimicrobial to an individual animal with a subclinical infection to reduce the risk of the infection becoming clinically apparent, spreading to other tissues or organs, or being transmitted to other individuals.
  • On a population basis, control is the use of antimicrobials to reduce the incidence of infectious disease in a group of animals that already has some individuals with evidence of infectious disease or evidence of infection.

Antimicrobial treatment of disease:

  • Treatment is the administration of an antimicrobial as a remedy for an individual animal with evidence of infectious disease.
  • On a population basis, treatment is the administration of an antimicrobial to those animals within the group with evidence of infectious disease.
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