Shoppers at some supermarket delis might get their next pound of salami with a side of bacteria.
A recent study from Purdue University found supermarket and grocery delis aren’t doing enough to eliminate harmful bacteria in ready-to-eat meats that can sicken healthy eaters and even kill customers with weak immune systems.
The bacteria also can reside in prepared salads and cheeses but is most associated with deli meats.
“This is a public health challenge,” said Haley Oliver, assistant professor of food science at the university, who led the study.
Oliver’s team examined 30 supermarket delis over six months in New York, North Carolina and Indiana. Researchers swabbed surfaces that would come into frequent contact with food, such as meat slicers and counters, and surfaces that typically don’t, such as floors and drains.
She found that 27 of the 30 delis had at least one sample test positive for a called Listeria monocytogenes, a subspecies of the bacterium Listeria. Twelve delis had at least three or more samples test positive.
She declined to name the national supermarket chains that participated in the study. Purdue did not examine stand-alone delis or franchise sandwich shops such as Subway or Quiznos.
Oliver said that Purdue is expanding its research to study an additional 100 delis.
The bacteria could lead to a potentially deadly infection called Listeriosis in people with weakened immune systems such as pregnant women, cancer and HIV patients, infants and children, Oliver told the Washington Examiner.
Healthy people are at a much lower risk, as this type of bacteria rarely causes food poisoning symptoms such as diarrhea and an upset stomach.
Listeriosis causes about 1,600 illnesses and 260 deaths a year in the U.S., according to the Centers for Disease Control and Prevention. The largest U.S. outbreak occurred in 2011 when 147 people were sickened and 33 were killed from eating contaminated cantaloupe, the CDC said.
Unlike other food-related pathogens such as salmonella and E. Coli, Listeria monocytogenes can grow at refrigerator temperatures, making it very persistent.
Even though there is a small sample size, Oliver said the results show a trend that the bacterium is prevalent in supermarket delis.
“The reason we haven’t had a Listeriosis outbreak tied to a deli is because it’s a disease with a long incubation time [21 days], and it’s difficult to track to a source,” she said in a statement.
The best way for consumers to avoid any health problems is to reheat their deli meats through a microwave or frying pan, as the bacteria can be killed easily by heat, Oliver said.
People with weakened immune systems should avoid ready-to-eat deli meats altogether or only buy pre-packaged meats, she added.
Supermarket delis need to do their part to install systematic and rigorous cleaning procedures, Oliver said. They should go beyond regular cleaning because the bacteria can flourish in areas not cleaned often, she added.
Oddly enough, Oliver and her team found most of the bacteria on surfaces not used for cooking, such as floors, drains and, curiously enough, squeegees.
The bacteria can be easily transferred unintentionally from these surfaces to food, such as when a worker bends down to tie his or her shoe and some bacteria from the floor gets on the gloves. The worker then doesn’t change gloves and inadvertently contaminates the meat, Oliver said.
More regulatory oversight may be needed, Oliver said. Meat processing plants are inspected regularly by state or federal inspectors for Listeria but those same controls don’t trickle down to the retail level, she added. Supermarkets are typically inspected by their local or county health departments.
