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U.S. Department of Health and Human Services

Animal & Veterinary

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Antimicrobial Drugs: Judicious Use Fights Resistance

By Dr. Melanie McLean, Senior Writer/Editor, Communications with contributions from Dr. William Flynn, Senior Advisor for Science Policy, and Dr. Diane Heinz, Director of the Policy & Regulations Staff, Office of the Center Director

On June 28, 2010, FDA’s CVM issued a draft guidance entitled “The Judicious Use of Medically Important Antimicrobial Drugs in Food-Producing Animals.” That title is a mouthful! To understand the purpose and importance of the draft guidance, several terms in its title need to be defined. 
Antimicrobial drugs” are drugs that work against a variety of micro-organisms, such as bacteria, viruses, fungi, and parasites. Antimicrobial drugs that work specifically against bacteria are called “antibacterial drugs,” or more commonly, “antibiotics.”   
Medically important antimicrobial drugs” are antimicrobial drugs that are important for treating infectious diseases in people. Most medically important antimicrobial drugs are antibiotics that treat infections in people caused by bacteria.
Judicious use” is using an antimicrobial drug only when necessary and appropriate.
Antimicrobial resistance” is when bacteria are no longer susceptible to an antimicrobial drug, meaning that the drug, and similar drugs, will no longer work against those bacteria. Antimicrobial resistance is also called “antibiotic resistance” or “drug resistance.” 
Antimicrobial resistance occurs after bacteria are exposed to an antimicrobial drug and continue to survive in the drug’s presence. Once bacteria become resistant to a drug, the continued use of that drug may increase the number of resistant bacteria. This is because only the susceptible bacteria are killed by the drug, leaving just the resistant ones. 
Food-producing animals” are animals that produce food, such as meat, milk, and eggs, for human consumption. Cattle, pigs, chickens, and turkeys are food-producing animals.

Purpose of Draft Guidance

CVM issued the draft guidance to address antimicrobial resistance and promote judicious use. The focus is on medically important antimicrobial drugs that are important therapies for bacterial infections in people. The draft guidance:

  • Discusses FDA’s public health concerns about how certain uses of medically important antimicrobial drugs in food-producing animals may impact antimicrobial resistance;
  • Summarizes some of the key scientific reports on the use of antimicrobial drugs in animal agriculture; and
  • Outlines FDA’s recommendations to ensure that medically important antimicrobial drugs are used judiciously in food-producing animals and remain effective for animals and people.

Implications of Antimicrobial Resistance

Antimicrobial drugs have been widely used in human and veterinary medicine for more than 50 years with great benefits to both people and animals. However, resistance to antimicrobial drugs and the resulting loss of effectiveness of these drugs are serious public health threats. Drug-resistant bacteria that enter the food supply in or on food products made from animals may add to antimicrobial resistance in people. 


Uses of Antimicrobial Drugs in Food-Producing Animals

Antimicrobial drugs that are FDA-approved for food-producing animals are currently used to:

  • Treat or control an on-going infectious disease;
  • Prevent an infectious disease before an outbreak occurs; or
  • Increase production by making the animal gain weight faster (increased rate of weight gain) and by improving the animal’s ability to convert the food it eats into growth (improved feed efficiency). Typically, no disease is present and no outbreak is anticipated. Rather, these drugs are given to animals so they make food for people faster and more efficiently.   
In the draft guidance, CVM states that using medically important antimicrobial drugs to increase production in food-producing animals is not a judicious use. 
CVM’s Judicious Use Recommendations
CVM’s draft guidance includes recommendations for the judicious use of antimicrobial drugs in food-producing animals. CVM recommends using medically important antimicrobial drugs in food-producing animals only when it is necessary for animal health and a veterinarian is involved. If followed, CVM’s recommendations will reduce the overall use of medically important antimicrobial drugs. If these drugs are used less, the risk of resistance developing is also less. 
The goal of CVM’s judicious use recommendations is to protect the health of animals and people by reducing drug resistance. CVM does not want the recommendations to negatively impact animal health or disrupt the animal agriculture industry.
“Judiciously using medically important antimicrobial drugs is key to minimizing resistance development and preserving the effectiveness of these drugs as therapies for humans and animals,” said CVM’s Director Dr. Bernadette Dunham. “CVM is committed to working with animal drug sponsors, the veterinary and public health communities, the animal agriculture industry, and others in the public in coming up with a practical strategy to address antimicrobial resistance concerns that is protective of both human and animal health.”

To read the Questions and Answers on CVM’s draft guidance, please visit:

The comment period on the draft guidance ends August 30, 2010. 

Submit electronic comments to http://www.regulations.gov. Submit written comments to the Division of Dockets Management (HFA-305), Food and Drug Administration, 5630 Fishers Lane, rm. 1061, Rockville, MD 20852.