Download Overuse of Antibiotics in Food Animal Production: Science Fact Sheet

A fact sheet from
May 2014
Overuse of Antibiotics in Food Animal
Production: Science Fact Sheet
We believe that there is a preponderance of evidence that the use
of antimicrobials in food-producing animals has adverse human
consequences … There is little evidence to the contrary.”
Government Accountability Office, 2004
Summary
Based on decades of scientific data, U.S. and international governmental organizations have concluded that the
overuse of antibiotics in food animal production contributes to human antibiotic resistance. Nearly 30 million
pounds of antibiotics were sold in the United States for use in livestock and poultry in 2011—almost four times
the amount sold for treating sick people.1
According to the U.S. Food and Drug Administration: “It is well established scientifically that all uses of
antimicrobial drugs, in both humans and animals, contribute to the development of antimicrobial resistance, and
that this is an important public health concern. Experts agree that antimicrobial drugs must be used ‘judiciously’
in both animal and human medicine to slow the development of resistance.”2
The research on antibiotic use in food animals contributing to the growing health crisis of antibiotic resistance
in humans dates back more than 40 years. Below are highlights from this significant body of literature, including
testimony of federal officials, reviews of peer-reviewed journal articles, and individual examples from within the
studies.
Recent testimony of federal agency officials
During House hearings in July 2010, FDA, the U.S. Centers for Disease Control and Prevention and the U.S.
Department of Agriculture affirmed the definitive scientific evidence that the overuse of antibiotics in food animal
production contributes to the development of antibiotic-resistant bacterial infections in people.
•• A USDA deputy administrator testified, “USDA believes that it is likely that the use of antibiotics in animal
agriculture does lead to some cases of antibacterial resistance among humans.”3
•• An FDA principal deputy commissioner testified, “The overall weight of the available evidence to date
supports the conclusion that using medically important antimicrobial drugs for production purposes is not in
the interest of protecting and promoting the public health.”4
•• CDC gave similar testimony, and the head of the agency wrote a follow-up letter to earlier statements
affirming, “studies related to salmonella, including many studies in the United States, have demonstrated that
(1) use of antimicrobial agents in food animals results in antimicrobial resistance in food animals, (2) resistant
strains are present in the food supply and commonly transmitted to humans, and (3) increases in resistant
strains result in adverse human health consequences (e.g., increased hospitalization).” 5
Major government reviews
•• The CDC stated in 2014 that “because of the link between antibiotic use in food-producing animals and the
occurrence of antibiotic-resistant infections in humans, antibiotics should be used in food-producing animals
only under veterinary oversight and only to manage and treat infectious diseases, not to promote growth.”6
•• The Government Accountability Office concluded in 2011 that antibiotic-resistant bacteria can spread from
animals and cause disease in humans through a number of pathways.7 The GAO had concluded from a 2004
review of existing data that antibiotic-resistant bacteria have been transmitted from animals to humans and
pose a significant threat to human health: “[Scientific studies] demonstrate a relationship between the use
of antimicrobials in food-producing animals, antibiotic resistance in humans, and adverse human health
consequences as a result. We believe that there is a preponderance of evidence that the use of antimicrobials
in food-producing animals has adverse human consequences. … There is little evidence to the contrary.”8
•• A 2003 joint report by the Food and Agriculture Organization of the United Nations, the World Organization
for Animal Health, and the World Health Organizationconcluded: (1) “There is clear evidence of adverse
human health consequences due to resistant organisms resulting from non-human usage of antimicrobials”;
(2) “the foodborne route is the major transmission pathway for resistant bacteria and resistance genes from
food animals to humans, but other routes of transmission exist”; and (3) the “consequences of antimicrobial
resistance are particularly severe when pathogens are resistant to antimicrobials critically important in
humans.”9
•• A 2003 report by the Institute of Medicine the health arm of the National Academy of Sciences,
recommended that “FDA ban the use of antimicrobials for growth promotion in animals if those classes of
antimicrobials are also used in humans.”10
•• A 1997 report by WHO stated that based on the weight of existing scientific evidence, “low-level, long-term
exposure to antimicrobials may have greater selective potential than short-term, full-dose therapeutic use”
and recommended ending the use of important human antibiotics for growth promotion in food animals.11
•• A 1988 study by the Institute of Medicine found a considerable body of indirect evidence implicating both
subtherapeutic and therapeutic use of antimicrobials in food animals as a potential human health hazard.12
•• A 1970 task force review by FDA acknowledged evidence showing that antibiotic use in food-producing
animals, especially in subtherapeutic amounts, was associated with the development of drug-resistant
bacteria, and that treated animals might serve as a reservoir of antibiotic-resistant pathogens that could
produce human disease.13
Highlights from individual studies and journal reports
•• A January 2014 study found that rural patients living within one mile of an industrial farm raising more than
2,500 hogs who were admitted to Veterans Affairs hospitals in Iowa were three times more likely to be
carrying methicillin-resistant Staphylococcus aureus, or MRSA, than other rural veterans.14
•• Two studies in 2013 found that people working on or living near pig farms or agricultural fields fertilized with
pig manure were more likely to become infected with MRSA. In the first study, those who had the highest
exposure to manure were 38 percent more likely to acquire MRSA in the community, and 30 percent were
more liable to become infected with it in a hospital. The second study found that 8 percent of pigs raised on
confinement operations and 87 percent of the workers there carried MRSA, whereas no such bacteria were
detected among pigs or people on antibiotic-free operations.15
•• A 2012 study used genetic fingerprinting technology to trace the origin of one strain of MRSA that was
spreading among livestock and humans in Europe and the United States. It concluded that humans passed
a drug-susceptible strain of Staphylococcus aureus to animals. Once in livestock exposed to antibiotics, the
bacteria developed resistance and now have been shown to spread from livestock to people.16
•• A 2010 study from the Public Health Agency of Canada showed that voluntary withdrawal of extralabel (for
reasons not indicated on the label) cephalosporin use in poultry resulted in a dramatic decrease in related
drug resistance in chicken Salmonella Heidelberg and E. coli, and a similar drop in drug-resistant Salmonella
Heidelberg infections in people. A partial reintroduction of the drug in hatcheries caused a rise in drugresistant E. coli.17
•• A 2007 study by the CDC and the U.S. Department of Veterans Affairs in Minnesota found that antibioticresistant E. coli in people was likely to have come from poultry.18
•• Studies in 2001, 2008, and 2012 suggest that drug-resistant E. coli strains in the human urinary tract may
come from livestock.19
•• A 2003 federal study found that a specific strain of salmonella infection in New England rose from 0 to 53
percent between 1998 and 2001, showed resistance to several antimicrobials used in livestock, and mirrored
the same infections in cattle.20
•• A 1999 Minnesota study reported that ciprofloxacin-resistant Campylobacter was found in 14 percent of
domestic chicken products, and that the number of related human infections had increased, largely because of
poultry consumption.21
•• A 1984 study by the U.S. Public Health Service, FDA, and Seattle-King County found that tetracycline-resistant
Campylobacter appeared “to flow from chickens to man via consumption of poultry products.”22
Endnotes
1
U.S. Food and Drug Administration, “2011 Summary Report on Antimicrobials Sold or Distributed for Use in Food-Producing Animals”
(Feb. 5, 2013), http://www.fda.gov/downloads/ForIndustry/UserFees/AnimalDrugUserFeeActADUFA/UCM338170.pdf.
2 U.S. Food and Drug Administration, “Strategy on Microbial Resistance—Questions and Answers,” accessed April 11, 2012, http://www.
fda.gov/AnimalVeterinary/GuidanceComplianceEnforcement/GuidanceforIndustry/ucm216939.htm.
3
John Clifford, then-deputy administrator of the Animal and Plant Health Inspection Service, U.S. Department of Agriculture, “Antibiotic
Resistance and the Use of Antibiotics in Animal Agriculture; Testimony Before the House Subcommittee on Health, Energy, and
Commerce,” 111th Cong., July 14, 2010.
4 Joshua Sharfstein, then-principal deputy commissioner of FDA, “Antibiotic Resistance and the Use of Antibiotics in Animal Agriculture;
Testimony Before the House Subcommittee on Health, Energy, and Commerce,” 111th Cong., July 14, 2010.
5 Thomas Frieden, director of the U.S. Centers for Disease Control and Prevention, “Antibiotic Resistance and the Use of Antibiotics in
Animal Agriculture; Testimony Before the House Subcommittee on Health, Energy, and Commerce,” 111th Cong., July 14, 2010.
6 Centers for Disease Control and Prevention, “Antibiotic Resistance Threats in the United States, 2013” (Sept. 16, 2013), http://www.cdc.
gov/drugresistance/threat-report-2013/pdf/ar-threats-2013-508.pdf.
7 Government Accountability Office, Antibiotic Resistance: Agencies Have Made Limited Progress Addressing Antibiotic Use in Animals (Sept. 14,
2011), http://www.gao.gov/assets/330/323090.pdf.
8 Government Accountability Office, Antibiotic Resistance: Federal Agencies Need to Better Focus Efforts to Address Risks to Humans From
Antibiotic Use in Animals (April 22, 2004), http://www.gao.gov/new.items/d04490.pdf.
9 Food and Agriculture Organization of the United Nations, World Health Organization, World Organization for Animal Health, “Expert
Workshop on Non-Human Antimicrobial Usage and Antimicrobial Resistance: Scientific Assessment,” Geneva, Dec. 1-5, 2003, https://
archive.org/stream/328496-joint-fao-oie-who-expert-workshop/328496-joint-fao-oie-who-expert-workshop_djvu.txt.
10 Institute of Medicine, Microbial Threats to Health: Emergence, Detection, and Response (Washington, DC: The National Academies Press,
March 15, 2003), http://www.nap.edu/catalog.php?record_id=10636.
11 World Health Organization, “The Medical Impact of Antimicrobial Use in Food Animals” (Oct. 17, 1997), http://whqlibdoc.who.int/
hq/1997/WHO_EMC_ZOO_97.4.pdf.
12 Institute of Medicine, Human Health Risks With the Subtherapeutic Use of Penicillin or Tetracyclines in Animal Feed (1988).
13 U.S. Food and Drug Administration, “The Use of Antibiotics in Animal Feed” (1970).
14 M. Carrel et al., “Residential Proximity to Large Numbers of Swine in Feeding Operations Is Associated With Increased Risk of MethicillinResistant Staphylococcus aureus Colonization at Time of Hospital Admission in Rural Iowa Veterans,” Infection Control and Hospital
Epidemiology 35, no. 2 (Feb. 2014): 190–3, doi:10.1086/674860, http://www.ncbi.nlm.nih.gov/m/pubmed/24442084/.
15 J. Casey et al., “High-Density Livestock Operations, Crop Field Application of Manure, and Risk of Community-Associated MethicillinResistant Staphylococcus aureus Infection in Pennsylvania,” JAMA Internal Medicine 173, no. 21 (2013): 1980–90, doi:10.1001/
jamainternmed.2013.10408, http://archinte.jamanetwork.com/article.aspx?articleid=1738717.; T.C. Smith et al., “Methiciliin-Resistant
Staphylococcus aureus in Pigs and Farm Workers on Conventional and Antibiotic-Free Swine Farms in the USA,” PLoS ONE 8, no. 5 (2013):
e63704, doi:10.1371/journal.pone.0063704, http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0063704.
16 L.B. Price et al., “Staphylococcus aureus CC398: Host Adaptation and Emergence of Methicillin Resistance in Livestock,” mBio 3, no. 1
(2012): e00305-11, doi:10.1128/mBio.00305-11, http://mbio.asm.org/content/3/1/e00305-11.
17 L. Dutil et al., “Ceftiofur Resistance in Salmonella enterica Serovar Heidelberg From Chicken Meat and Humans, Canada,” Emerging
Infectious Diseases, 16 (2010): 48-54.
18 J.R. Johnson et al., “Antimicrobial Drug-Resistant Escherichia coli From Humans and Poultry Products, Minnesota and Wisconsin, 20022004,” Emerging Infectious Diseases (June 2007), doi:10.3201/eid1306.061576, http://wwwnc.cdc.gov/eid/article/13/6/06-1576_article.
htm#suggestedcitation.
19 A.R. Manges, “Widespread Distribution of Urinary Tract Infections Caused by a Multidrug-Resistant Escherichia coli Clonal Group,”
New England Journal of Medicine 345, no. 14 (2001): 1007–13, doi:10.1056/NEJMoa011265, http://www.nejm.org/doi/full/10.1056/
NEJMoa011265; T.J. Johnson et al., “Comparison of Extraintestinal Pathogenic Escherichia coli Strains From Human and Avian Sources
Reveals a Mixed Subset Representing Potential Zoonotic Pathogens,” Applied and Environmental Microbiology 74, no. 22 (2008): 7043–50,
doi:10.1128/AEM.01395-08, http://aem.asm.org/content/74/22/7043; and A.R. Manges and J.R. Johnson, “Food-Borne Origins of
Escherichia coli Causing Extraintestinal Infections,” Clinical Infectious Diseases 55, no. 5 (2012): 712–9, doi:10.1093/cid/cis502, http://cid.
oxfordjournals.org/content/55/5/712.
20 A. Gupta et al., “Emergence of Multidrug-Resistant Salmonella enterica Serotype Newport Infections Resistant to Expanded-Spectrum
Cephalosporins in the United States,” Journal of Infectious Diseases 188, no. 11 (2003): 1707–16, doi:10.1086/379668, http://jid.
oxfordjournals.org/content/188/11/1707.full.
21 K.E. Smith et al., “Quinolone-Resistant Campylobacter jejuni Infections in Minnesota, 1992-1998,” New England Journal of Medicine 340
(1999): 1525–32, doi:10.1056/NEJM199905203402001, http://www.nejm.org/doi/full/10.1056/NEJM199905203402001.
22 U.S. Public Health Service, U.S. FDA, U.S. Bureau of Veterinary Medicine, Seattle-King County Department of Public Health,
Communicable Disease Control Section, Surveillance of the Flow of Salmonella and Campylobacter in a Community (1984),
For further information, please visit:
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Email: [email protected]
Phone: 202-887-8801
Project website: saveantibiotics.org
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