Paula Fedorka-Cray shifts uncomfortably in her seat when asked whether banning the routine use of medication in feed to boost livestock performance would help prevent the increase in drug-resistant bacteria.
That’s a matter for policy makers, said the microbiologist, who specializes in antimicrobial resistance research for the United States Department of Agriculture in Athens, Georgia.
There’s no question that resistance has spread around the globe, she said, and become a major concern for human and animal health.
But Fedorka-Cray said there’s not enough information about the effects of removing subtherapeutic medication from livestock feed.
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In fact, researchers lack a great deal of information when it comes to understanding the causes, effects and spread of antimicrobial resistance, she said.
“In some ways, we’re back here in the Stone Age,” Fedorka-Cray told farmers at the Manitoba Swine Seminar in Winnipeg on Jan. 31.
Until the mid-1990s, there was a lack of monitoring programs for antimicrobial resistance.
Fedorka-Cray is part of the National Antimicrobial Resistance Monitoring System, or NARMS, set up in 1995 to monitor resistance in pathogens found in
humans and livestock.
NARMS’s purpose is to describe resistance and give information to doctors and veterinarians so they can make decisions about how to prolong the lifespan of drugs, and how to research the causes of resistance.
The team of scientists is looking at campylobacter, E.coli 0157:H7 and salmonella, an ubiquitous bacteria with more than 2,300 types.
The team collects livestock samples from research and diagnostic labs, as well as slaughter plants.
So far, Fedorka-Cray said resistance to tetracycline is most common.
The team has also found bacteria resistant to several types of antimicrobials.
One strain of salmonella typhimurium DT104 that is causing concern is resistant to ampicillan, chloramphenicol, streptomycin, sulfonamides and tetracycline.
Resistant strains of bacteria emerged soon after penicillin was released in the 1940s, Fedorka-Cray said, but small numbers of resistant bacteria can be eliminated by the immune system.
To become more prevalent, resistant bacteria need a way to multiply and expand. It is believed that low levels of antimicrobials help create conditions where resistant bacteria survive and can propagate.
Resistant bacteria didn’t become a problem until medication became more widely available.
Misuse wasn’t common when a doctor wielding a long needle administered penicillin, she said. But today, it’s common for people to save medication rather than take the prescribed course, and self-medicate later on.
Using low levels of antimicrobials in livestock feed and water to prevent disease and improve performance raises similar concerns.
“This is the area that is causing the greatest degree of heartburn in the medical community.”
However, she said it’s important for people outside the agricultural community to understand the benefits of subtherapeutic medicine use, and the problems of trying to administer medication to individual animals.
She said she has demonstrated this to other scientists by taking them into a barn of 20,000 chickens, challenging them to pinpoint the sick bird, and then catching it to administer the medication.
“It’s like the herding cat phenomenon,” she told producers, describing how the poultry immediately crowd together on the opposite side of the barn.
Fedorka-Cray encouraged farmers to spend time telling people how they raise their livestock so others can understand the challenges.
