Antimicrobial Use in Food Animals: Addressing a Public Health Crisis

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Antimicrobial Use inFood AnimalsAddressing a
Public Health Crisis

• Maryland Patient Safety Conference
• Baltimore, MD

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Margaret Mellon Ph.D., J.D.
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The Nature of the Crisis

• Antibiotics the miracle drugs of the 20th
  century no longer work as well as they once
  did.
• The reason is the evolution of resistance due to
  use.

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When Antibiotics Fail

• Combinations of drugs
• More toxic drugs
• More expensive drugs
• Longer time to recover
• Sometimes death

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Few New Drugs in the Pipeline

• Process to develop new drugs 800M, 10 years
• Only two novel classes in last 20 years
• New drugs much more expensive
• Not a panacea, certainly not soon

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Two Major Sources of Resistance

• Use in human medicine Use in animal
  agriculture

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Where Does Resistance in Animals Develop?

• In populations of bacteria
• Animal guts (including humans) are filled with
  live bacteria
• The guts of animals fed antibiotics in food and
  water are filled with resistant bacteria

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Routes of Exposure

• On food Salmonella, Campylobacter, Enterococci
• Through workers and nearby communities
• Through the environment

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We Use the Same Drugs in Humans and Food Animals

• Penicillins, Tetracyclines, Erythromycin,
• Sulfa drugs
• Bacteria that are resistant to these important
  drugs build up in cows, pigs and chickens

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The Problem is in Production

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CAFOs

• Confined Animal Treatment Operations
• (CAFOs)
• Antibiotics
• Bovine Growth Hormone
• Arsenicals

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Beyond the Residue Issue

• Antibiotic drug residues in meat and milk are of
  concern but have been addressed
• The generation of antibiotic-resistant bacteria
  back on the CAFO has not been addressed

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New Policy Use Antibiotics Wisely

• Use only where necessary
• Always use judiciously

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Reduce Antibiotic Use Everywhere Possible

• Judicious Use
• Human therapy
• Food animal therapy
• Companion animal therapy
• Eliminate Use
• Non-therapeutic purposes in food animals
• Consumer products

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Purposes for Food Animal Use

• Therapy for sick animals
• Growth promotion or feed efficiency
• Routine disease prevention

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Antimicrobial Use in the U.S. UCS Estimates
71

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8
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Livestock Therapy
Human Therapy
Other
Livestock Non-Therapeutic
More than eight times as much to healthy animals
as to sick people
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Key Finding

• About 24 million pounds of antimicrobials every
  year in cattle, pigs, chickens, and turkeys that
  are not sick
• About 3 million pounds of antimicrobials used in
  humans

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The Connection

• What is the evidence for the connection
  between antibiotic use in food animals and
  difficult-to-treat diseases in human medicine?

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Alliance for the Prudent Use of Antibiotics
(APUA) Report

• Facilitated a review and examination of
  literature
• Reviewed and analyzed hundreds of papers
• Took several years to deliberate
• Published in a peer-reviewed journal
• Clinical Infectious Diseases 34S71-72, 2002

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Major Conclusion of APUA Report

• Antimicrobial Agents Should Not be Used
• in Agriculture in the Absence of Disease

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Urinary Tract Infection

• E. coli Eight million urinary tract infections
  a year in the U.S.
• 22 of UTIs resistant to trimethoprim-sulfamethoxa
  xole in a recent study
• One clonal group accounted for 1/3 to 1/2 of
  isolates
• Appeared simultaneously in three locations
• Animal use is likely source of resistance

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Enough is Enough

• New England Journal of Medicine
• World Health Organization
• Centers for Disease Control and Prevention
• Alliance for the Prudent Use of Antibiotics
• American Medical Association

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Time to Stop
New England Journal of Medicine 3451202-03,
10/18/01 (editorial)
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Now What?

• Good science isnt enough to change public policy.

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Keep Antibiotics Working

• Union of Concerned Scientists
• Environmental Defense
• Center for Science and the Public Interest
• Institute for Agriculture and Trade Policy
• Humane Society of the United States
• Food Animal Concerns Trust

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Keep Antibiotics Working

• www.keepantibioticsworking.com
• Public Education
• Eat Well Guide
• Legislation
• Agencies FDA, USDA
• Private Sector McDonalds, Tysons
• Media

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New Legislation

• Phase out nontherapeutic use of medically
  important antibiotics
• Allow livestock operators to treat sick
  animals

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Nontherapeutic Use

• Use in the absence of disease
• Growth promotion
• Feed efficiency
• Routine disease prevention

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Medically Important

• Penicillins
• Tetracyclines
• Macrolides (Tylosin and Erythromycin)
• Lincomycin
• Aminoglycosides
• Sulfonamides
• Virginiamycin

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European Experience

• Banned all growth promoters in food animals
• Carefully studied the effects of withdrawal
• No adverse effect on animal health, producer
  profits or consumer prices
• Some increase in therapeutic drug use

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The Preservation of Antibiotics for Medical
Treatment Act

• Phase out the use of medically important
  antibiotics for non-therapeutic purposes
• Transition payments to small and medium-size
  farmers
• Data collection

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Endorsers

• Over 300 organizations, including
• American Medical Association
• American Public Health Association
• American College of Preventive Medicine
• American Academy of Neurology
• American Nurses Association
• Academy of Medical-Surgical Nurses
• National Association of Pediatric Nurses
• National Gerontological Nurses Association

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EndorsersState Nursing Associations

• Florida Nurses Association
• Ohio Nurses Association
• Connecticut Nurses Association
• Mississippi Nurses Association
• Oklahoma Nurses Association
• South Carolina Nurses Association
• South Dakota Nurses Association

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EndorsersState Medical Associations

• Medical Society of the District of Columbia
• Minnesota Medical Association
• Montana Medical Association
• New Hampshire Medical Society
• New Mexico Medical Society
• Tennessee Medical Association
• Maine Medical Association
• Vermont Medical Society

• Connecticut State Medical Society
• Wisconsin Medical Society
• Florida Medical Association
• Idaho Medical Association
• Iowa Medical Society
• Louisiana State Medical Society
• Massachusetts Medical Society
• Medical Society of New Jersey
• Oregon Medical Association
• Medical Society of Virginia

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Thank you!
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EXTRA SLIDES
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Arguments Against Restricting Antibiotic Use in
Food Animals

• No proof of connection
• Raise the cost of meat
• Increase the number of sick animals
• Reduce the safety of the meat supply
• We have no other way of producing food animals

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Preservation of Medical Antibiotics Treatment Act
PAMTA

• S.549
• H.R.962

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STAAR

• Strategies To Address Antimicrobial Resistance
  Act (STAAR)
• S.2313
• H.R.3697

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E. Coli

• Study of urinary tract infections in university
  health centers in CA, MN, MI
• Approximately one in five resistant to
  trimethoprim-sulfamethoxazole
• One clonal group accounted for 1/3 to 1/2 of
  isolates
• Simultaneous outbreaks
• Authors concluded that most likely source is
  contaminated food

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Resistance Transfer

• Unlike higher organisms, bacteria can transfer
  genes to unrelated bacteria.
• Plasmids
• Plasmid transfer not rare
• Confirmed in human gut, mouth
• Bacteria can teach each other to outwit
  antibiotics.

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Multi-Drug Resistant Salmonella typhimurium
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Challenges

• Two major sources of exposurehuman and animal
  use
• No baselines
• Clinical failure vs. increased resistance
• Very little monitoring and surveillance

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Kinds of Evidence

• Increased level of resistance in disease-causing
  organisms
• Cases in which a disease outbreak is traced to a
  specific animal source (most in Europe)
• FDA fluoroquinolone risk assessment

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Resistance Levels in Animal Bacteria Fell
Dramatically After Phase-out
Aarestrup et al., Anti-microbial Agents and
Chemotherapy, 2001 45(7). 2054-59
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Other Drugs Used in Animals

• Used for growth promotion, disease prevention
• Not used in human medicine
• Too toxic
• Roughly half of the antimicrobial use in food
  animals