Study Finds Enterococcus Bacteria
Resistance In People Not Related
To Antibiotic Use In Cattle
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by Agriculture and Agri-Food Canada
r. Tim McAllister, a principal research scientist at the Agriculture
and Agri‑Food Canada Research and Development Centre in
Lethbridge, Alberta, says that, he and his team have found nothing
to indicate that antimicrobial resistance (AMR) in beef cattle is being
transmitted to humans.
The recent study was published in the academic journal
Scientific Reports.
“Antimicrobial resistance is a serious concern for both animal
and human health, and part of addressing those concerns is
understanding whether there are any linkages between the two,”
says Dr. McAllister. “So, at least as far as beef cattle are concerned,
this is a significant finding.”
Dr. McAllister is among close to two dozen scientists at five different
federal departments and agencies, Alberta Agriculture and Forestry
and the University of Calgary involved in a series of interlocking
research projects aimed at understanding whether antibiotic use in
the beef, pork and poultry industries is increasing the risk of AMR
in humans—and if so, what steps can be taken to reduce the risk.
The five‑year Genomics Research and Development Initiative‑AMR
project, launched in 2016, is a major component of the Federal Action
Plan on Antimicrobial Resistance and Use in Canada. The project
also required coordination with feedlot veterinarians, commercial
feedlot operators and was partially funded by the Beef Cattle Research
Council Cluster.
Focusing on the beef industry, Dr. McAllister collaborates with
researchers in other departments in taking a “One Health” approach
to the issue.
“Basically, that’s just recognizing there are no borders when it comes
to AMR,” says Dr. McAllister. “Bacteria with AMR can be found in
humans, in animals, and in the environment, and they may spread
from one to the other. That’s why, in our research, we’re looking at
bacteria from people being treated for infections in hospitals, from
cattle in feedlots, from waterways, from processing plants, sewage
plants and elsewhere to see where and what type of AMR exists, and
whether we can make any connections from one to the other.”
Using the highly detailed molecular data that can be acquired
through whole genome sequencing, Dr. McAllister’s team has
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determined that the Enterococcus bacteria found in cattle and the
Enterococcus that poses a serious threat to human health are actually
entirely different species of bacteria.
“We have also discovered that the genes responsible for AMR in
the Enterococcus bacteria in humans are associated with antibiotics
that are never used in cattle—in other words, it is becoming clear that
AMR in cattle is the result of antibiotics used in cattle, and AMR in
Enterococcus bacteria found in humans is the result of antibiotics
used in humans.”
At the same time, he cautions that you can never say never.
“There are billions of cells out there and they are masters of
adaptation, so there’s always a chance,” says Dr. McAllister. “We have
tried really hard to find the smoking gun—that link of AMR and beef
to humans—and we have not. Still, we can’t rule out that there could
be a very lucky shot some time in the future. The chances of that
happening are very, very low, but they’re not zero.”
Industry welcomes “important step forward”
Genomics research funded through the Genomics Research and
Development Initiative and the Beef Cattle Research Council has yet
to find any evidence that antimicrobial resistance in beef cattle is being
transmitted to humans. At the Beef Cattle Research Council, Science
Director Dr. Reynold Bergen says Dr. McAllister’s research represents
an important contribution to the development of science‑based policy
and regulations on the use of antimicrobials in food production.
“AMR is a major concern for people and for the beef industry, and
something the industry has been researching for more than 20 years,”
says Dr. Bergen. “We need antimicrobials to continue to work in
people when they get sick, and we need them to work in cattle when
they get sick. Dr. McAllister’s research is an important step forward—
with no evidence that AMR is being transferred from cattle to people,
or vice versa, we can bring new focus to our research, based on the
understanding that, although we must continue to use antimicrobials
responsibly in both human medicine and cattle production, AMR in
humans and AMR in cattle are separate issues.”
• APRIL 2020