Drug-resistant bacteria found in Canadian grocery store squid

Bug found in Chinese grocery in Canada, the first of its kind discovered in a food product

PUBLISHED : Friday, 13 June, 2014, 5:30am
UPDATED : Friday, 13 June, 2014, 5:30am

Researchers in Canada have discovered an antibiotic-resistant bacteria for the first time in a food product - raw squid found in a Chinese grocery store - widening the potential exposure for consumers, according to a report published by the US Centres for Disease Control and Prevention.

Until now, most antibiotic-resistant bacteria have been in health-care settings and spread by infected patients, as occurred in the superbug outbreak at the National Institutes of Health clinical centre 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 hospitalised," said Joseph Rubin, assistant professor of veterinary microbiology at the University of Saskatchewan, who authored the study published on Wednesday.

"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 travelling or following hospitalisation," 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 are not properly cleaned.

The bacteria 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 defence, Rubin said.

Bacteria that have this capability are dangerous because if they are present in a person's body, they can share that gene or enzyme with other bacteria. That, in turn, 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 people 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 Chinese grocery store in Saskatoon. They included two squids, two packages of frog legs and two packages of black sea cucumber.

Only one squid, a whole frozen one that was about 20-30cm long, showed presence of the microbe, Rubin said. Rubin said he did not know whether the squid acquired the bacteria during food processing and handling or from its natural environment.