Researchers in Canada have discovered one of the deadliest kinds of antibiotic-resistant bacteria for the first time in a food product — raw squid — widening the potential exposure for consumers, according to a report published Wednesday by the U.S. Centers for Disease Control and Prevention.
Most antibiotic-resistant bacteria have, until now, been in health-care settings and spread by infected patients, as occurred in the “superbug” outbreak at the National Institutes of Health clinical center in 2011 that killed seven people.
The discovery of such a microbe in food means “the risk of exposure in the public goes beyond people with travel histories and beyond people who have been previously hospitalized,” said Joseph Rubin, assistant professor of veterinary microbiology at the University of Saskatchewan.
“This finding means a much broader segment of the population is potentially at risk for exposure. It’s something you may be bringing into your home rather than something you would acquire while traveling or following hospitalization,” he said.
Cooking the squid at the proper temperature would kill the bacteria. But the bacteria could still spread into humans through cross-contamination if kitchen surfaces and hands aren’t properly cleaned.
The bacterium found in the squid is a common environmental organism, present in dirt and water. But in this case, scientists found that it had a gene that made it resistant to antibiotics that are considered the last line of defense, Rubin said.
Bacteria that have this capability are dangerous because if they are in a person’s body, they can share that gene or enzyme with other bacteria. And that makes those other bacteria also resistant to these last-resort antibiotics, known as carbapenems.
The organism found in the squid, Pseudomonas fluorescens, probably would not make a healthy person sick, Rubin said. But for those with immune systems compromised by chemotherapy or illness, it could make common bacteria like E. coli resistant to the last-resort antibiotics. E. coli is the most common cause of urinary tract infections in healthy people.
The organism was found in a package of frozen squid purchased at a Chinese grocery store in Saskatoon, Canada, in January. The store owner said the squid came from South Korea.
“Finding this organism in food is extremely disturbing,” Rubin said. “This widens the possibilities for the spread of resistance.”
As part of a pilot study, Rubin and other researchers bought six food samples from the Saskatoon store, including two squids, two packages of frog legs and two packages of black sea cucumbers.
Only one squid — a whole, frozen one between 8 and 15 inches — showed the presence of the microbe, Rubin said. Rubin said he doesn’t know whether the squid acquired the bacteria during food processing and handling or from its natural environment. Researchers will continue testing dozens of other food samples from other specialty stores, he said.
Researchers said they chose to sample foods in niche markets because the scope of antimicrobial drug-resistance surveillance programs in the United States and Canada is limited to such products as poultry, beef and pork. But as communities become increasingly diverse, “niche-market meat products, including imported foods, are becoming increasingly common,” Rubin said.
Health officials around the world have warned about the rising threat from antibiotic resistance. The CDC warned last fall that the United States faces “potentially catastrophic consequences” if it doesn’t act quickly to combat the growing threat of antibiotic-resistant infections, which kill about 23,000 Americans a year.
“Whenever we see last-resort antibiotics, such as carbapenems, stop working for another type of bacteria — we are highly concerned,” Jean Patel, deputy director of the CDC’s Office of Antimicrobial Resistance, said in a statement. “Losing carbapenems could mean we are facing completely untreatable infections.”