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Worrying increase in antimicrobial drug use in US livestock

Domestic sales and distribution of antimicrobials approved for use in food producing animals in the US increased by 22% from 2009 through 2014. This is stated in the latest FDA report on this topic.

Each year, every sponsor of an approved or conditionally approved application for a new animal drug containing an antimicrobial active ingredient must report to the US Food and Drug Administration (FDA) the amount of each such ingredient in these drug products sold or distributed for use in food-producing animals. FDA summarises this information and makes it available to the public in annual summary reports.

Preventive and curative

There are different reasons to administer antimicrobial drugs. In the US, they can be used for growth promotion, to prevent disease or to treat sick animals. In 2014, sales and distribution (domestic and export) of antimicrobials approved for use in food producing animals was approximately 15.4 million kilogrammes in 2014. The majority of the drugs are formed by tetracyclines (43%) and ionophores account for 31% of domestic sales. In 2014, the majority of the drugs (62%) were formed by antibiotic classes that are considered by the FDA to be important for human health. Of the total volume of this type of drugs used, tetracyclines accounted for 70%, penicillins for 9%, macrolides for 7%, sulfonamides (sulfas) for 5%, aminoglycosides for 3%, lincosamides for 2%, fluoroquinolones for less than 1%, and cephalosporins for less than 1%. In 2014, the use of antimicrobial drugs, that are not currently medically important for human health, accounted for 38% of the domestic sales of all antimicrobials approved for use in food producing animals. 80% of these were ionophores.

Trends over the last years

From the data in the FDA report, it can be concluded that the total domestic sales and distribution of antimicrobials approved for use in food producing animals increased by 22% from 2009 through 2014, and increased by 4% from 2013 through 2014. The use of medically important antimicrobials saw an increase of 3% from 2013 through 2014. The use of antimicrobial drugs for non-medically important reasons increased by 20% between 2009 and 2014, with an increase of 5% from 2013 through 2014.

Antibiotic resistance

The overuse of antibiotics can contribute to the development of resistant bacteria (also called superbugs). Estimates show that up to 2 million Americans per year are affected by superbugs, with over 23,000 killed due to their untreatable nature, according to the Centers for Disease Control and Prevention (CDC).

Read the full FDA report


  • S Roach

    Nice graphs but the text has some inaccuracies.

    Antimicrobials can still be used in the US for growth promotion not only for prevention and treatment. The current FDA plan is to have the drug makers voluntarily remove growth from the approved indications by the end of this year but they have not yet done so.

    Also the 62% is for medically important drugs meaning that they are in classes that FDA considers important for human health. It tells you nothing about how they are used in animals.

    We do not know what proportion of this 62% is used for growth promotion, disease prevention, or treatment. Most of the drug classes have approvals for all three and we do not collect farm level data on quantities used by purpose, Since most are sold over the counter there is nowhere the reason for use is even written down.

  • Emmy Koeleman

    Dear S Roach, thank you for the comments. I will have a look at the inaccuracies you mention.

  • Emmy Koeleman

    Dear S Roach, as you can see, the text and figures have now been changed.

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