Ranchers and farmers have been feeding antibiotics to the animals we eat since
they discovered decades ago that small doses of antibiotics administered daily
would make most animals gain as much as 3 percent more weight than they
otherwise would. In an industry where profits are measured in pennies per
animal, such weight gain was revolutionary.
Although it is still unclear exactly why feeding small "sub-therapeutic" doses
of antibiotics, like tetracycline, to animals makes them gain weight, there is
some evidence to indicate that the antibiotics kill the flora that would
normally thrive in the animals' intestines, thereby allowing the animals to
utilize their food more effectively.
The meat industry doesn't publicize its use of antibiotics, so accurate
information on the amount of antibiotics given to food animals is hard to come
by. Stuart B. Levy, M.D., who has studied the subject for years, estimates that
there are 15-17 million pounds of antibiotics used sub-therapeutically in the
United States each year. Antibiotics are given to animals for therapeutic
reasons, but that use isn't as controversial because few argue that sick
animals should not be treated.
The biggest controversy centers around taking antibiotics that are used to treat human illnesses and administering them to food animals. There is an increasing amount of
evidence suggesting that the sub-therapeutic use of antibiotics in food animals
can pose a health risk to humans. If a group of animals is treated with a
certain antibiotic over time, the bacteria living in those animals will become
resistant to that drug. According to microbiologist Dr. Glenn Morris,
the problem for humans is that if a person ingests the resistant bacteria via
improperly cooked meat and becomes ill, he or she may not respond to antibiotic
Concern about the growing level of drug-resistant bacteria has led to the
banning of sub-therapeutic use of antibiotics in meat animals in many countries
in the European Union and Canada. In the United States, however, such use is
still legal. The World Health Organization is concerned enough about antibiotic
resistance to suggest significantly curbing the use of antibiotics in the
animals we eat. In a recent report, the WHO declared its intention to "reduce
the overuse and misuse of antimicrobials in food animals for the protection of
human health." Specifically, the WHO recommended that prescriptions be required for
all antibiotics used to treat sick food animals, and urged efforts to
"terminate or rapidly phase out antimicrobials for growth promotion if they are
used for human treatment."
Although conclusive evidence directly linking the use of drugs in food animals
to an increase in drug-resistant bacteria that make people sick has not been
uncovered, a number of recent studies suggesting such a link concern many
scientists. "There is no evidence that antibiotic resistance is not a problem,
but there is insufficient evidence as to how big a problem it is," says Dr.
Margaret Mellon, with the Union of Concerned Scientists.
In one study published in the New England Journal of Medicine on February 6, 2002,
researchers found links that strongly suggested that the people who developed
Cipro-resistant bacteria had acquired them by eating pork that were
contaminated with salmonella. The report concluded that salmonella resistant to the antibiotic flouroquine can be spread from swine to humans,
and, therefore, the use of flouroquinolones in food animals should be prohibited.
Another New England Journal of Medicine study from Oct. 18, 2001, found that 20
percent of ground meat obtained in supermarkets contained salmonella. Of that
20 percent that was contaminated with salmonella, 84 percent was resistant to
at least one form of antibiotic.
Cipro and Baytril
Some, including the FDA, believe the overuse of Baytril, an antibiotic used to treat sick birds, led to an increase in treatment-resistant bacterial infections in humans. Baytril is used by poultry growers to protect chickens and turkeys from E. coli infection. The size of commercial chicken
flocks precludes testing and treating individual birds, so when a veterinarian
diagnoses one infected bird, farmers treat the whole flock by adding the drug
to its drinking water. General use of Baytril, therefore, falls in the gray
area between therapeutic and sub-therapeutic.
Baytril is the sister drug to Cipro, which is used to treat and prevent anthrax as well as campylobacteriosis and salmonellosis in people. The Food and Drug Administration, doctors, and consumer groups have all
urged that Baytril be removed from the market on the grounds that its use in
animals may eventually compromise the power of Cipro and similar antibiotics to
fight disease in humans. Cipro and Baytril belong to a class of drugs known as
fluoroquinolone, among the most powerful antibiotics currently available.
Baytril first came up for approval for use in chickens six years ago.
Physicians have used fluoroquinolones to treat food-borne illness since 1986,
but fluoroquinolone-resistant bacteria were rare until 1995, when the FDA
approved the use of these drugs in drinking water for poultry. The FDA's rough
estimate, using 1999 data, is that use of fluoroquinolones in chickens resulted
in over 11,000 people that year contracting a strain of the campylobacter
illness that was resistant to fluoroquinolones, contributing to unnecessarily
When the FDA proposed pulling Baytril use in chickens a year ago due to sharp
increases in resistance to fluoroquinolones in campylobacter bacteria, one of
the two manufacturers voluntarily withdrew its product. The
other, Bayer, did not.
Bayer officials continue to offer the human drug Cipro at reduced rates to the
American public, saying that they are not convinced that the use of
fluoroquinolones in animals can be blamed for increased resistance in people.
Until more proof is found of the specific danger to humans, they will not
withdraw their product from the chicken market.
The Meat Industry's Argument
For its part, the meat-production industry contends that there is not enough
conclusive evidence to support measures like the FDA's proposed ban against
flouroquinolones. Although none deny that the spread of antibacterial
resistance is a real problem, proponents of sub-therapeutic antibiotic use in
animals point out that the problem stems from overuse of all antibiotics,
including therapeutic and preventative use in both animals and humans.
Agricultural use may contribute to the problem, but it is impossible to
determine to what extent.
In its recent report, the World Health Organization blamed the worldwide
upswing in resistance to antibiotics on a combination of factors that included
"overuse in many parts of the world, particularly for minor infections," and
"misuse due to lack of access to appropriate treatment." The factors involved
in the problem are clearly not limited to antibiotic use in animal feed.
"When someone's sick and goes to the doctor, they still expect to get a
prescription," said National Chicken Council spokesman Richard Lobb. He said
that people should look to themselves for the causes of antibiotic resistance, referring to the American practice of prescribing antibiotics for even the most minor of illnesses.
Increased use in hospitals may also contribute to the resistance problem.
"Today, especially in intensive care wards, the amount of antibiotics in the
environment can become high enough that people in the vicinity of patients
receiving antibiotics are exposed continuously to low levels of antibiotics,"
microbiologist Abigail Salvers of University of Illinois told Scientific
American. This low level of exposure, she contends, is one reason why
highly resistant bacteria are developing in hospitals. She says that a similar
phenomenon may be taking place in agriculture.
According to Alexander S. Matthews, president and CEO of the Animal Health
Institute (AHI), removal of antibiotics from animals' feed and water "would
lead to increased animal disease, a reduction in food safety and gain little,
if anything, in the effort to control resistance." He suggests developing
"prudent use principles."
Lowering or halting sub-therapeutic antibiotic use in animal production could
have serious economic effects on the meat and poultry industry. According to a
report released in May 2001 by USDA's Economic Research Service,
discontinuing the use of antimicrobial drugs in hog production would initially
decrease feed efficiency, raise food costs, reduce production and raise prices
to consumers. According to the same report, U.S. hog producers saved about $63
million in feed costs in 1999 due to their use of low levels of sub-therapeutic
drugs; they would have suffered an estimated loss of $45.5 million in 1999 if
the drug use was banned.
Even within the industry, however, there is a growing movement to reduce at
least the sub-therapeutic use of antibiotics in animals raised for food.
Tyson Foods, Perdue Farms and Foster Farms, which collectively produce a third
of the chicken Americans eat, recently declared their intention to greatly reduce the
amount of antibiotics fed to healthy chicken. There is still no way for
consumers to know whether one of these companies' chickens has been treated
with antibiotics, although some corporate consumers, McDonald's, Wendy's and
Popeye's among them, are refusing to buy chicken that has been treated with
fluoroquinolones. Increased public pressure may cause the companies who grow animals for food to collectively decide that putting extra weight on feed animals isn't worth the possibility that they are putting consumers' health at risk.
REPORTS & GOVERNMENT SITES
· The Use of Drugs in Food Animals: Benefits and Risks
This book, commissioned by the USDA and published in 1999, addresses the many
benefits and risks associated with using antibiotics in feed animals. In the
chapter titled "Costs of Eliminating sub-therapeutic Use of Antibiotics," the
authors conclude that if there were a ban on sub-therapeutic drug use, the
annual cost to consumers would be between $4.84 and $9.72 per capita.
· WHO: Global Strategy for Containment of Antimicrobial Resistance
This September 2001 report from the World Health Organization blames a
combination of factors for the worldwide upswing in resistance to antibiotics,
including widespread overuse and misuse. As for the use of antibiotics in food
animals, the authors say that "inefficient and inadequately enforced regulatory
mechanisms regarding antimicrobial supply contribute to excessive and
inappropriate drug use." The authors observe that the incidence of
antibiotic-resistant campylobacter in live poultry has increased dramatically,
and that resistant strains of salmonella have been detected in several
countries worldwide. Earlier, in June 2000, the WHO released a major report
titled "Overcoming Microbial Resistance." Here is the press release for that report, along with
audio links to expert
opinions about the report's findings.
· Antimicrobial Drug Use and Veterinary Costs in U.S. Livestock
According to this report, released in May 2001 by the USDA's Economic Research
Service, discontinuing the use of antimicrobial drugs in hog production would
initially decrease feed efficiency, reduce production, and
raise consumer prices. The author says that U.S. hog producers saved about
$63 million in feed costs in 1999 due to their use of low levels of
· CDC: Antimicrobial Resistance
This is the CDC's site dedicated to the issue of antimicrobial resistance. Elsewhere,
the CDC publishes another site about antibiotics, Promoting Appropriate Antibiotic Use in the Community.
Both sites have plenty of background information.
· FDA: Antimicrobial Resistance
A website under the auspices of the FDA's Center for Veterinary Medicine, the
antimicrobial resistance section of this site includes FDA fact sheets and
consumer information about drug resistance. Elsewhere on the FDA website is
this site on antibiotic resistance, which
has general background as well as links to additional resources.
· "Growing Resistance"
The author of this article from the December 2000 issue of Mother Jones
asks, "Is agribusiness squandering one of medicine's most potent weapons?" (Mother Jones, November/December 2000)
· "The Challenge of Antibiotic Resistance"
"Certain bacterial infections now defy all antibiotics. The resistance problem
may be reversible, but only if society begins to consider how the drugs affect
'good' bacteria as well as 'bad.'" (Scientific American, March 1998)
· "Where's the Beef on Farm Antibiotics?"
In this article written by the publisher of JunkScience.com and published on
FoxNews.com, the author argues that evidence to link the use of antibiotics in
food animals to human health problems is scant. "Bacterial resistance to
antibiotics is on the rise. ... So far, the only cause that everyone agrees
about is that physicians hand out antibiotics like candy," writes the author. (FoxNews.com, Jan. 12, 2001)
DEFENSES OF ANTIBIOTIC USE
· Beef.org: Myths and Facts About Beef Production
Beef.org, the website for the National Cattlemen's Beef Association and the
Beef Board, includes this backgrounder on antibiotic use in cattle. It says
that "no residues from feeding antibiotics are found in beef, and there is no
valid scientific evidence that antibiotic use in cattle causes illness
resulting from the development of antibiotic-resistant bacteria."
· The Coalition for Animal Health
This October 2001 press release from the Coalition for Animal Health, which
includes the National Cattlemen's Beef Association, the National Chicken
Council, and the National Pork Producers Council, says that "the use of U.S.
FDA-approved antibiotics in animals has been verified in scientific studies
through the past 40 years as providing a critical, first line of defense to
keep our nation's food supply safe and secure."
· Animal Health Institute
The Animal Health Institute, which represents companies that make drugs for
farm animals, publishes this fact sheet about animals and antibiotics,
in which it says that "there is no documented case where antibiotic use in
animals has caused treatment failure in people."
· Montana State University: Beef Briefs
A beef specialist at MSU contends that there is no valid scientific evidence
that feeding antibiotics to beef cattle leads to health problems in people.
This is a brief overview of his position, along with his list of supporing sources.
ORGANIZATIONS & ADVOCACY GROUPS
· Alliance for the Prudent Use of Antibiotics
The website for APUA, a 20-year-old advocacy group that promotes the proper use
of antibiotics, is an excellent resource for information about drug resistance.
APUA collaborates on projects with other organizations such as the U.S. Agency
for International Development and the World Health Organization. Its site
provides practical information for the consumer as well
as in-depth information for practitioners.
APUA's Project FAAIR (Facts About
Antibiotics in Animals and Their Impact on Resistance) crafted this flow chart tracking
the several ways that antibiotics migrate from animals to humans.
Keep Antibiotics Working is a coalition of health, consumer, environmental, and
agricultural groups that is working to end what it deems the "overuse and
misuse" of antibiotics in animal agriculture. It has compiled summaries and
links to key scientific evidence
supporting the coalition's position.
· Center for Science in the Public Interest: Antibiotic-Resistance
CSPI is a Washington, D.C.-based advocacy group that promotes food-safety
awareness. Its Antibiotic-Resistance Project website includes links to several
articles, including "Protecting the Crown Jewels of Medicine," its strategic plan
for preserving the effectiveness of antibiotics. The site also has a
legislative and regulatory update, which tracks new
· Union of Concerned Scientists: Antibiotic Resistance
The Union of Concerned Scientists is a nonprofit alliance of scientists and
other concerned individuals across the country. Among other things, the website
for the group's antibiotic resistance project has a glossary of terms and
background information on the FDA's approach to antibiotic regulation.
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