Scientists have found a previously undetected drug-resistant bacterium in the North American food supply.

Routine testing of raw squid that was for sale in Saskatoon, Canada revealed a carbapenem-resistant strain of bacteria. Carbapenem is a "last resort" antibiotic, given to patients for whom more common antibiotics have failed. As resistance to our last line of defense grows, public health officials caution that we may get closer to being unable to treat some infections.

The location -- a grocery store -- is troubling to researchers, as it potentially expands the exposure risk from a relatively small slice of the public to a much larger sector.

"Finding the bacteria in food is particularly concerning because it means that the risk for exposure for the public extends beyond people who have a particular travel history, or people who have recently been hospitalized," principal investigator Joseph Rubin, an assistant professor at the University of Saskatchewan in Saskatoon, Canada told The Huffington Post. "Many people bring food products into their homes, obviously, so if we find this in the food products, it's a big concern."

The bacterium itself, Pseudomonas fluorescens, is not necessarily dangerous to people with healthy immune systems, explained Rubin. However, the microorganism he discovered carries a gene that produces the enzyme carbapenemase, which makes it resistant to Carbapenems.

It's that gene, as well as bacteria's ability to exchange genes with other bacteria, that makes the microorganism so potentially dangerous.

"Bacteria can share DNA with each other, so finding these genes in really any organism is concerning because it means that they're potentially available to many different organisms, including pathogens," said Rubin.

The CDC calls antibiotic resistance "one of the world's most pressing public health problems" and says that over time, almost every bacteria out there has become more resistant to antibiotics.

Unchecked, antibiotic-resistant bacteria could lead to even more infections that are difficult to treat and easy to pass on to other people.

Rubin's team discovered the bacteria last January in one of two packages of raw frozen squid that were tested. The seafood was most likely imported from South Korea, according to a press release. Researchers tested it alongside other products like frog legs and black sea cucumber, which were not contaminated.

The researchers didn’t determine how the bacteria got into the squid, so it's too early to contemplate food industry-wide interventions, said Rubin. But, he added, the discovery means public health officials need to expand tracking and testing of more varied types of food products. Currently, inspectors in North America generally limit themselves to testing for antibiotic-resistant bacteria for high-demand products: beef, pork, chicken.

Previous and unrelated testing of grocery store items has revealed contamination of other types of antibiotic-resistant bacteria. Most notably, a 2013 Consumer Reports investigation found that half of supermarket chicken samples were contaminated with a drug-resistant bacterium.

Each year in the U.S., at least two million people get infected with antibiotic-resistant bacteria, and at least 23,000 people die because of those infections, according to a 2013 report by the CDC.

Rubin also hopes his research is a wake up call for consumers to improve their food safety protocols at home. He urges home cooks to prevent cross-contamination between raw meat and ready-to-eat food, wash their hands and cook meats to safe internal temperatures.

"Like any food-borne illness, those are really going to be the best defense against bacteria and these genes getting into consumers," said Rubin.