Understanding the origins of antibiotic-resistant foodborne illness

In 2016, the World Health Organization recognized antibiotic-resistant bacteria as a global “fundamental threat.” Researchers at the University of Minnesota Center for Animal Health and Food Safety (CAHFS) and Veterinary Diagnostic Laboratory (VDL) have partnered with the Minnesota Department of Health to better understand how bacteria develop antimicrobial resistance (AMR).

"Minnesota was one of the first states to study human and animal health together and the University of Minnesota had a lot to do with that,” says Kirk Smith, DVM, MS, PhD, an adjunct professor at the University of Minnesota School of Public Health (SPH) and manager of the Foodborne, Waterborne, Vectorborne, and Zoonotic Diseases Section at the Minnesota Department of Health (MDH). “We've always been a model of collaboration.”

It’s more important than ever to understand how animals, humans, and the environment all play a part in the rise of AMR genes, since the Centers for Disease Control and Prevention estimates over one million Americans are affected by Salmonella each year. Some strains of antimicrobial resistant Salmonella have emerged, and these strains of Salmonella are especially dangerous to human and animal health. The partnership between the University and the state focuses on sequencing strains of the bacteria, one of the most common foodborne pathogens in the world.

MDH has a long history characterizing foodborne pathogens on the human side. The department is one of 10 FoodNet sites tracking foodborne illness around the country.

“A few years ago we started working with CAHFS and that is taking the research to a much different level,” says Dave Boxrud, Enterics Unit supervisor at the MDH Public Health Laboratory.

Salmonella can come from virtually anywhere. It’s commonly found in animals and in the environment. It can get into food manufacturing plants where it can contaminate packaged foods like peanut butter. Because it has such a broad range of sources, researchers have struggled to identify the main sources for Salmonella in humans, something MDH seeks to understand through the partnership.

As Albert Rovira, DVM, PhD, of the University of Minnesota Veterinary Diagnostics lab explains, CAHFS is the link connecting his work identifying Salmonella in animals with MDH’s work, which does the same in humans.

Understanding the parallels will ultimately help determine from which sources—specific animals or environmental players—humans are contracting Salmonella. If researchers can understand this, they’ll have a better shot at stopping the spread of AMR.

DNA of different subtypes of Salmonella found in humans, animals, and the environment were analyzed together. From the data, the teams could identify which strains were potentially resistant to antimicrobials, and through which of several processes those strains developed their resistance. They could also determine if the strains they were seeing emerge in animals were the same ones emerging in people.

"One of the best things about the collaboration between CAHFS, the VDL, and MDH is that we can take advantage of more of the information we're generating. In this case, it can benefit public health," says Rovira, who explains that because research is focused in nature, data sets often harbor information that can be useful to researchers with different goals in mind; but that information is often not utilized.

By understanding how AMR behaves in Salmonella, we can better understand how AMR works in other bacteria.

“We have two groups that are interested in the same organism but from different viewpoints, so it's important for us to work together so we can use our data more effectively," says Boxrud.

See all - One to One Newsletter: Fall 2018

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CAHFS News is a compilation of current topics and news updates in animal health, food safety, and veterinary public health.