Curiosity abounds after antibiotic resistant gene found on farm

Research published in early December last year by Ohio State University animal scientists detailed the discovery of an antibiotic-resistant gene in a farrowing barn. Since its announcement, the industry has responded in various ways, ranging from curiosity to disappointment to calls for further testing.

Thomas Wittum, Ph.D., is chair of the Department of Preventative Veterinary Medicine at Ohio State, in charge of the team behind the discovery of the antibiotic-resistant gene on the production pig farm, the location and ownership of which has not been released.

“We have national surveillance in place looking for important antibiotic resistant organisms in farms. As part of that surveillance, we detected what’s known as a Carbapenem-resistant isolate on a pig farm here in the U.S. That’s a really important type of resistant bacteria because we usually only expect to find those organisms in human hospitals. So they’ve never been observed on farms before in the U.S. The fact that this was present on a farm was really surprising,” Wittum said.

According to a press release from the American Society for Microbiology, “This combination of attributes, and the fact that carbapenem resistance was recently designated an urgent threat to public health by the Centers for Disease Control and Prevention led the researchers to investigate whether bacteria with carbapenem resistance genes such as bla-imp-27 might be present in agricultural animals or in agricultural settings.”

The discovery came after investigators collected environmental and fecal samples from the 1,500-sow farrow-to-finish farm over a window of four visits in five months. The resistant bacteria were found growing in agar plates as a result.

A particularly surprising piece of the study came from the fact that no new livestock were introduced on the farm in the past 50 years, as they have been breeding their own stock in that time.

Many producers are curious about how such a unique organism found its way to a hog operation.

“We’re not really sure,” Wittum said. “We believe it got introduced. Probably by the movements of people or animals in some way, but we’re just not sure where it came from. It originally evolved in a human hospital or some other place and then introduced onto this farm.”

The good news from the study — published in a journal of the American Society for Microbiology — was that no meat was contaminated nor humans infected with the bacteria. Wittum said there was no evidence that pigs carried the gene into the human food supply.

The farm’s protocol was examined to get more information. Wittum said the operation in question was concerned about animal health, but professionals are working with them now to establish more secure practices.

“Some of the things that we do on farms to treat sick piglets also can favor the spread of these resistant organisms. So sometimes we have to change our standard practices, maybe things like rotating antibiotics or other approaches veterinarians can help with, just to be sure that even though we may be treating appropriately, we may still be providing selection pressure that allows these organisms to spread,” he said. “They’ve been working with their veterinarian and we’ve been discussing with them some of their antibiotic use practices. That might’ve been helping to slow the spread of these resistant organisms.”

The discovery comes as no mere accident, as Ohio State has been part of a nationwide effort to monitor resistance in agriculture. Wittum said the focus on that research has grown exponentially in recent years.

“It’s a really important issue for a lot of reasons,” he said. “There’s definitely been more work looking at the relationship between resistance in animals and humans because we know that organisms that affect animals affect humans and vice versa. We can exchange those organisms whether they’re resistant or not. And so we need to understand how those organisms move between animal and human populations.”

As with any research, certain questions remain unanswered, including a big one.

“What we don’t know is how to control resistant organisms like this once they’re introduced into a farm,” Wittum said. “Because obviously the farmer doesn’t want it to be there and we don’t want to have a risk of it being introduced into the food supply. At this point we don’t know how to get rid of it so that’s one of the things we’d like to figure out.”

What sort of management should producers be doing now to make sure this isn’t a problem down the road on their own farms?

“Well obviously biosecurity is really important in farms in general, but swine producers in particular really have high levels of biosecurity,” Wittum said. “But that’s really important — to maintain that strong biosecurity to help prevent the introduction of pathogens or resistant organisms like this. They also need to work closely with their veterinarian to be sure they’re applying antibiotics in the right way and using the right approaches to be sure that we’re not providing selection pressure that favors the spread of these highly resistant organisms. Those are some of the things that farmers should pay attention to.”

Resulting from the discovery has been notable feedback from industry and consumer groups.

“Producers and farm organizations are concerned because of food safety concerns, but also because these resistant organisms are animal health concerns as well. If you have animals that are sick with these resistant organisms, then they may not be able to be treated with some important antibiotics,” Wittum said. “So definitely producers and veterinarians are very concerned about this.”

One high ranking veterinarian in particular pointed out that the development is the most recent in a time of vast antibiotic discussion in recent years, from both the producer and consumer perspectives.

“I’m chairman of the National Institute of Animal Agriculture for the next two years and we’ve had for the last six years the antibiotic symposium, involving the human medical field as well as the veterinary field and industry,” said Tony Forshey, State Veterinarian. He knows firsthand the importance of antibiotic effectiveness.

“We’ve been talking about how these bugs become antibiotic resistant and how they exchange DNA and genetics, and some of these bugs have never seen antibiotics before yet they carry that resistant gene,” Forshey said. “It’s survival of the fittest and they’re doing pretty well at that. We’ve got to come up with alternative ways other than antibiotics to manage disease. Those are some of the things we’re discussing.”

Forshey also said improvements are needed when talking about antibiotics with the public.

“Well I think we can. We don’t need to use fear tactics. Food safety is number one in this country in what we’re doing, and all of our meats and milks and other things are going into the marketplace and the food chain don’t have antibiotics in them. We talk about antibiotic-free and some of these things when really, that stuff has always been that way,” Forshey said. “We need to just approach it and get everybody involved and interact. We need to collaboratively talk about how these bacteria develop antibiotic resistance and how to get those genes through DNA exchange between the bacteria themselves. There’s a lot of reasons for this and there’s nobody really to blame. We just have to come up with alternatives.”

As the leader of animal health in Ohio, Forshey had some words of wisdom going forward.

“It’s a great time to be in the business of agriculture,” he said. “I’ve always been involved with ag, growing up on the farm. We take food safety very seriously. We take disease issues very seriously. So I think we’re doing a better job with the technology we have today in producing a better product everyday.”

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