Facts about Antibiotics and Agriculture

CBS News recently aired a story covering antibiotic use in livestock. There was also a recent New York Times opinion piece (link)with a similar point of view. The story seems to reflect popular stereotypes similar to those set by the Union of Concerned Scientists:

'A study by the Union of Concerned Scientists found that in the United States, 70 percent of antibiotics are used to feed healthy livestock.'

This is meaningless. What matters is, of the antimicrobials given to animals, what % actually target pathogens that affect humans. Most antibiotics used in the livestock industry are used for treating, controlling, and preventing disease. Only 13% are used to improve nutritional efficiency and enhance growth. Resistance requires selection pressure, and if the majority of antimicrobials used in livestock production are not selecting against deadly pathogens, then the risks are overblown. What we have observed is that in countries where feed grade antimicrobials used in livestock production have been more heavily regulated or banned, the resulting increase in livestock illness has lead to an increased use of antibiotics actually used in human medicine. In Denmark ( contrary to what was reported by CBS) where some feed grade antibiotics have been banned, an increased reliance on therapeutic usage (30%) has resulted because of the increase in animal sickness. The same thing happened in Sweden as well.

These policies resulted in increased selection pressure for antibiotic resistance among pathogens dangerous to humans. Similar policies in the U.S. should be avoided.
Despite fears related to antibiotic use in livestock and resistance in humans, no conclusive scientific link has been found.


References:

Doyle et al., Institute of Food Technologists, “Antimicrobial Resistance: Implications for the Food System” Comprehensive Reviews in Food Science and Food Safety, Vol.5, Issue 3, 2006.

"Microbiological Quality of Ground Beef From Conventionally-Reared Cattle and "Raised without Antibiotics" Label Claims" Journal of Food Protection, July 2004,Vol 67 Issue 7 p. 1433-1437

Journal of Antimicrobial Chemotherapy, 2003

The Environmental Safety and Benefits of Growth Enhancing Pharmaceutical Technologies in Beef Production. Alex Avery and Dennis Avery, Hudson Institute, Centre for Global Food Issues.

Animal Health Institute

'The Spread of Superbugs.' Nicholas D. Kristoff. New York Times. March 6,2010