Overuse of antibiotics in farm animals is the focus of government health
agencies
BOSTON - THURSDAY, JUNE 25, 1998

IDEAS, SCIENCE

Controlling Bacteria on the Farm

Peter Spotts
Staff writer of The Christian Science Monitor
Send e-mail to: pspotts@compuserve.com

ITHACA, N.Y.

To improve meat safety, the federal government for years has allowed
ranchers and farmers to feed antibiotics to beef, cattle, and poultry to
control bacteria deemed harmful.

That practice, however, is coming under increasing criticism from some
consumer groups and public-health organizations. Overreliance on
antibiotics down on the farm, they say, may be contributing to a larger
public-health problem: the excessive use of antibiotics in medicine and
consumer products in general.

The trend, they say, is giving rise to bacteria that resist the
antibiotics used to treat humans for the diseases associated with the
microscopic organisms. Some of these antibiotics also are used as food
and water additives to ward off illness and boost the meat yield in
livestock.

"In certain cases, there are fewer and fewer antimicrobials available to
treat serious diseases in humans," says Sharon Thompson, an associate
director in the US Food and Drug Administration's Center for Veterinary
Medicine in Rockville, Md.

------------------------------------------------------------------------
The concern centers on farmers' routine use of antibiotics. Its use on
livestock accounts for roughly half of the 25,000 tons produced in the
United States each year.
------------------------------------------------------------------------



At issue, researchers say, is not the use of antibiotics to combat
specific disease outbreaks among livestock. Instead, the concern centers
around farmers' routine use of antibiotics. Livestock use accounts for
roughly half of the 25,000 tons of antibiotics produced in the US each
year, according to a report last month from the Institute of Medicine.
It adds that 40 to 80 percent of the antibiotics applied on the farm are
unnecessary.

So far, evidence that the use of antibiotics in agriculture is having
significant adverse off-farm effects is inconclusive, according to the
Animal Health Institute, a pharmaceutical-industry organization based in
Washington D.C.

Speaking at a veterinary meeting in College Park, Md., earlier this
year, Richard Carnevale AIH vice president noted that while antibiotic
resistance in general is a problem, "how much of it is really due to
animal drugs and what is the medical impact?... The problem is complex,"
and "the risks of using animal drugs must be put in context with the
real risk factors associated with food-borne illness."

Still, the AIH acknowledges that available studies "are suggestive" that
"injudicious use" of antibiotics on the farm can lead to the development
of treatment-resistant strains of unwanted bacteria.

Nor is the concern confined to the US. Earlier this month, the World
Health Organization, based in Geneva, held a meeting to look at the
impact of using a class of antibiotics known as fluoroquinolones to
treat farm animals as well as people. Several countries approving the
compound for use in agriculture noted that food-borne bacteria have
become less susceptible to the antibiotic. WHO outlined an ambitious
research agenda for members to pursue to assess the antibiotic's effects
and to develop alternative treatments.

Antibiotics, or antimicrobials, are compounds formulated to kill or slow
the growth of bacteria. Initially, they were derived from natural
sources. With advances in molecular biology, however, pharmaceutical
companies now add man-made components to an antibiotic or design and
make the compounds synthetically.

Under this high-tech assault, bacteria evolve defensive mechanisms of
their own, explains Rodney Dietert, professor of immunotoxicology at
Cornell University's College of Veterinary Medicine in Ithaca, N.Y.
While an antibiotic may weaken or kill most of its target bacteria, some
survive and continue to reproduce, conferring their resistance on later
generations. Moreover, bacteria of one species can readily exchange
genetic material with bacteria of another species. Thus, they transmit
antibiotic resistance among potentially harmful species.

Finally, he says, "when you find bacteria that resists one antibiotic,
you often find that it can resist two or three others as well. It's
quite onerous."

How this bacterial "arms race" plays out in agriculture is the subject
of a National Research Council study due out next month. Although the
results are still being hammered out, the NRC says that it will be the
first "consensus" report that will try to determine how significant the
problem truly is.

Even if the farm connection is uncertain for now, the costs to society
of trying to deal with antibiotic-resistant bacteria are not. Those
costs run from $4 billion to $5 billion a year, according to the
Institute of Medicine in Washington.

Cornell's Dr. Dietert says that in his view, the routine applications he
finds troubling aren't necessary, if farmers use good animal-husbandry
practices.

Unless regulations governing the use of antibiotics on and off the farm
are tightened, "the crown jewels of modern medicine will turn to dust,"
says Patricia Lieberman, a physiologist and staff scientist with the
Center for Science in the Public Interest, a Washington-based consumer
group. Emerging evidence regarding farm-introduced resistance to
antibiotics may only be "the tip of the iceberg," she says.


Before bookmarking this page in your browser, click here.
The URL for this page is:
http://www.csmonitor.com/durable/1998/06/25/fp56s1-csm.htm

For further information:


* 'Miracle drugs' are losing ground to infections
* Inapropriate Use of Antibiotics Leads to Resistant Bacteria
* Scientific American: Ask the Experts
Please Note: The Monitor does not endorse the sites behind these links.
We offer them for your additional research.

Webmaster: steve@greenpeople.org