Feedstuffs Magazine
Resistance casts shadow on antibiotic regulatory decisions
By SALLY SCHUFF
Feedstuffs Washington Editor
November 12, 2001

HERSHEY, PA. -- Current changes in the scientific and regulatory climate

surrounding the use of antibiotics in livestock production were a major
discussion topic during last week’s meeting of the U.S. Animal Health
Assn.
(USAHA) here.

Dr. Paul Sundberg of the National Pork Board told USAHA's pharmaceutical

committee that the American Society of Microbiology (ASM), the nation’s
foremost scientific society on antibiotic issues, currently is
undertaking a
major investigation of antibiotic resistance issues in agriculture. ASM,
he
said, is in the process of laying the groundwork for a major report on
the
role of antimicrobials in agriculture. That report, according to
Sundberg,
will cover current antibiotic usage focused on animal agriculture, why
those
antibiotics are important, how they help and the consequences of
changing
the way they are currently used.

The ASM report is due out in late May 2002.

Sundberg said ASM is addressing the subject of antibiotics because it
recognizes the need for a benchmark scientific review of the issues.
"We’re
in a climate where we have regulatory decisions that need to be made,"
Sundberg said. "And, we’re in the mode that those are having an effect,
intended or unintended, on animal production and pharmaceuticals."

Sundberg said the ASM meeting was also an attempt to begin the major
collaborative effort that will be needed to have meaningful
surveillance,
diagnosis and risk management strategies.

The current regulatory climate will drive the need for pooling
scientific
expertise, Sundberg said. He said the ASM meeting held "promise for
bringing
together some of the people that can show us the direction we have to
go."

Among the new science that is clearly driving the regulatory climate are

several studies by the University of Maryland published last month in
the
New England Journal of Medicine. They will add impetus for ongoing and
additional studies of antibiotic use in meat and egg production.

The University of Maryland’s study that found salmonella in 20% of the
ground meat purchased at Washington, D.C., area grocery stores was
discussed
at the USAHA meeting by Dr. Stephen F. Sundlof, director of the Food &
Drug
Administration’s Center for Veterinary Medicine (CVM). That study, he
said,
found 13 serotypes of salmonella in 41 of 200 samples of retail ground
meats. Of the 41 salmonella isolates, which included 13 serotypes, a
total
of 84% were resistant to at least one antibiotic.

Sundlof reported that "16% were resistant to ceftriaxone -- the drug of
choice for treating children with salmonellosis -- a disturbing
finding."
The 17 antibiotics in the University of Maryland study were the same
antibiotics routinely surveyed in the ongoing National Antibiotic
Resistance
Monitoring System study.

The University of Maryland study also found multi-drug resistant
Salmonella
typhimurium DT 208 and 104 in the retail ground meat samples, Sundlof
said.
That is significant because the organisms can cause severe illness, he
reported, noting that they are "usually resistant to ampicillin,
chloramphenicol, streptomycin, sulfonamides and tetracyclines.

The antibiotic-resistant microbes were recovered from the meat before it
was
cooked. Nonetheless, the findings have prompted concern in the
scientific
community, he said.

The number of cases of DT 104 has increased worldwide, Sundlof said.

The Center for Disease Control & Prevention has reported that the
percentage
of isolates resistant to the antibiotics above has increased from 0.6%
in
1980 to 34% in 1996.

Sundlof said the isolation of DT 208 from ground meats "also is a
concern
because of the extensive patterns of resistance of this organism."

Another study of retail ground meat is currently underway at Iowa State
University. One of the scientists attending the USAHA meeting in Hershey

noted during discussion of antibiotic resistance at the pharmaceutic
committee meeting. He said the study also suggested "the use of
ceftiofur in
livestock accelerated the development of resistance to ceftriaxone in
salmonella."

Together with earlier studies, Sundlof said, the findings seem to
indicate
that "foods from animals are potential sources of ceftriaxone-resistant
salmonella that infects humans." The link, however, he said, has not yet

been made.

A concurrent study also published by the New England Journal of Medicine
has
prompted CVM to investigate the use of ceftiofur and gentamicin in
embryonated eggs, Sundlof reported. CVM suspects the egg production
practice
"contributes to ceftiofur and gentamicin resistance if the drug are used
on
the chickens and turkeys later in life."

CVM plans to poll producers using a questionnaire designed to gather
more
data. CVM epidemiologists will be reviewing the questionnaires for the
next
few months.

In a separate presentation, Dr. Eric Bush, an epidemiologist with NAHMS
located at Ft. Collins, Colo., reported on the survey of antibiotic use
in
swine. That survey is scheduled to be published in January and will be
on
the NAHMS web site.

Bush said the study showed that antibiotic usage can be measured, but
those
measurements do not accurately reflect a measurement of selection
pressure
for genetic resistance.

He said his survey concluded that livestock feed is the primary vehicle
used
for antibiotics intended to promote growth and prevent disease.

In another report, the committee also reviewed data from work done by
Dr.
Isabelle Moreau, a veterinarian who works with antibiotic-free pork
producers. Her report, presented at the meeting by pharmaceutical
committee
chairman Dr. Roy A. Schultz, suggested that while pigs could be raised
without antibiotics, cost increases of about 20% would occur due to
disease
and death loss.

Copyright 2001, The Miller Publishing Company, a company of Rural Press
Ltd.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
For SC email list T-and-C, send: GET TERMS-AND-CONDITIONS.CURRENT
to [log in to unmask]