Leafy Greens with Listeria Sold at Major Supermarkets

Posted on July 26, 2019 by


by Trisha Calvo

Consumer Reports found the bacteria in prewashed and unbagged products. Here’s how to stay safe when eating greens.

A new Consumer Reports test of 284 samples of fresh greens—such as lettuce, spinach, and kale—found six samples tainted with Listeria monocytogenes, a potentially deadly bacteria. The samples were purchased at several grocery store chains including Acme, Costco, Hannaford, and Whole Foods.

Two of these samples were packaged, prewashed greens—a spinach and an organic spinach-spring mix. The other four were loose heads or bunches of green kale, green leaf lettuce, red leaf lettuce, and spinach.

“While it may not be surprising to find listeria in a small percentage of leafy green products that are tested, it is always concerning to find bacteria that can make people sick in foods that aren’t meant to be cooked,” says Karen Wong, M.D., medical officer in the Centers for Disease Control and Prevention’s Enteric Diseases Epidemiology Branch.

CR’s study represents a snapshot of the market and was not large enough to draw conclusions about the safety of specific brands or retailers. But the testing underscores that industry needs to do more to improve the safety of leafy greens.

The supermarket industry has taken many steps to keep dangerous bacteria out of food, says Hilary Thesmar, Ph.D., senior vice president of food safety programs at the Food Marketing Institute, a trade association that represents retailers, wholesalers, and suppliers that sell products to grocery stores. Still, she said CR’s findings are “going to cause us to look more closely at the food safety program and have more conversations with our suppliers. And I think we can always improve our food safety programs.”

CR says that people can continue to eat leafy greens, which are packed with nutrients. “However, it’s important that those most likely to be affected by listeria—older adults, infants and young children, anyone with a compromised immune system, and pregnant women—carefully consider whether to eat raw leafy greens, including lettuce,” says James. E. Rogers, Ph.D., director of food safety research and testing at Consumer Reports. “The safest thing is to stick with greens you can cook.”

CR decided to test leafy greens for harmful bacteria because of several outbreaks linked to romaine lettuce and other leafy greens over the past few years. While we found listeria, we did not find other bacteria that cause foodborne illness, such as salmonella and E. coli O157:H7 in any of the 284 samples we tested.

All of the greens were purchased between June 3 and June 19, 2019 in Connecticut, New Jersey, and New York.

Of the six samples tainted with Listeria monocytogenes, one had a strain genetically linked to at least two cases of listeriosis (the illness caused by listeria) reported to the CDC. (We do not know if the people who got sick ate leafy greens.) That product was a “triple-washed” Nature’s Place Organic Spinach Spring Mix purchased at a Hannaford supermarket.

A spokesperson for Hannaford said that it had not received any reports of illness associated with that product.

The other products with listeria were purchased at:

• Acme—unbranded, unbagged red leaf lettuce

• Costco—bagged spinach from Boskovich Farms (marked “triple washed”)

• Hannaford—unbranded, unbagged spinach

• Whole Foods—unbagged green kale from Lancaster Farm and unbranded, unbagged green leaf lettuce.

Few people likely still have any of those products in their homes. But if you bought any of them in early or mid June, wash and sanitize your crisper drawer or anywhere else the greens may have been stored. “Listeria can survive for a long time on a variety of surfaces, and unlike other bacteria can continue to grow at refrigerated temperatures,” Rogers says. “If there is lingering listeria in your fridge, it could contaminate other foods. So thorough cleaning is important.”

CR’s Findings Trigger FDA Inspection

CR immediately informed the Food and Drug Administration and the CDC of our test results. We also contacted the companies that marketed the greens and the retailers where we purchased them.

In response to CR’s findings, the FDA initiated an inspection of the plant that produced Nature’s Place Organic Spinach Spring Mix, the product that contained a strain of listeria linked to two illnesses.

The FDA has a zero tolerance policy for Listeria monocytogenes: If the agency finds it during an inspection or a manufacturer finds it during testing, immediate action is required, which can include taking the product off the market.

Hannaford told CR the FDA had not “found anything of concern in its inspection,” and that “the supplier does extensive testing of its own.”

CR asked the FDA if its follow-up testing is complete, and hasn’t yet received a response. But a spokesperson for the agency told us earlier that “We continue to look at the data provided by Consumer Reports. The FDA takes the presence of harmful pathogens in our food supply very seriously and considers the risk to public health when taking action.”

While CR applauds the FDA’s inspection of the Nature’s Place plant, the agency should take other steps, too, Rogers says. ”Given the severity of listeriosis, our hope is that the FDA follows up on all the samples we found and not just the one linked to illnesses, in keeping with the agency’s zero tolerance policy,” he says.

As for the bulk spinach contaminated with listeria found at Hannaford, the company said: “The products identified are long past their sell-by dates and no longer in the stores. However, through an abundance of caution, we have conducted an additional deep clean of the display case where the bulk spinach was purchased.” Hannford also noted that, due to seasonal shifts in growing areas, its spinach supplier is sourcing from a different region now than it was when CR’s sample was purchased.

Boskovich Farms, which produced the other sample of bagged spinach found to be contaminated with listeria, told CR that it hasn’t received any reports of illness. It also said that when this lot of spinach was produced, inspections at the farm and at the processing plant showed no evidence of contamination.

The other retailers we contacted noted that food safety is their top priority and that consumers should wash unbagged leafy greens.

But washing may not remove all contaminants from fresh greens, according to CDC researchers and others in a recent article in the journal Emerging Infectious Diseases. “Washing is mainly helpful for getting rid of dirt and some pesticides, not bacteria,” says CR’s Rogers. “Bacteria can adhere to the surface of the leaves, and get stuck in microscopic crevices.”

Listeria monocytogenes is different from other types of bacteria that cause foodborne illness. “It’s one of the very few bacteria that can actually grow under refrigerator temperatures. That’s where we have extra trouble with listeria,” says Thesmar, at the Food Marketing Institute. In fact, she says, the cold, moist environments of refrigerators and food-processing facilities make ideal breeding grounds for the bacteria.

And while listeriosis isn’t as common as some other foodborne illnesses, it is often more serious. The CDC estimates 1,600 people develop the disease each year, compared with 1 million who become ill from salmonella in food. But almost everyone who develops the disease requires hospitalization and about 20 percent die, while less than half a percent of people infected with salmonella die.

Why are there so few listeria infections? Not everyone exposed to the bacteria gets sick from it. “It is rare for healthy adults to get sick with listeria infection,” the CDC’s Wong says. “Listeria primarily causes illness in pregnant women, newborns, older adults, and people with weakened immune systems.”

Pregnant women are 10 times more likely to get a listeria infection than other people. Although the women themselves may not become very ill, it can affect their fetuses: The bacteria can cause miscarriage, preterm labor, and stillbirth. About 25 percent of listeriosis cases in pregnant women result in the loss of the baby, according to the CDC.

Symptoms of listeria infection can include a fever, muscle aches, headaches, and diarrhea or other gastrointestinal symptoms. If the infection spreads to the nervous system, it can also cause a stiff neck, confusion, loss of balance, and convulsions.

Listeria is usually associated with deli meats, hot dogs, soft cheeses, and sprouts. But in recent years other types of foods have been linked to outbreaks of listeriosis, including leafy greens.

“Overall, we’re seeing more cases of foodborne illness linked to produce,” Rogers says. Nearly half of the foodborne illnesses that occurred between 1998 and 2008 were caused by produce, most often leafy greens, according to a 2013 CDC report.

And produce accounted for 30 to 60 outbreaks a year between 1998 and 2016, according to a recent analysis of CDC data published in Congressional Research Service. Leafy greens were responsible for 20 to 40 percent of those outbreaks. And outbreaks of E. coli 0157:H7, a dangerous strain, from leafy greens and romaine lettuce in 2017 and 2018, sickened a total of nearly 300 people in the U.S. More than a third of them were hospitalized, and six people died.

How to Stay Safe

While listeria is killed when it’s exposed to high temperatures, leafy greens are risky because they are often eaten raw.

Buying bagged, prewashed produce is no guarantee of safety, either. “Bagged produce should not have any pathogens in it, period,” Thesmar says. “Consumers should be able to eat that product out of the package.” But CR found listeria in two packaged, prewashed packages of leafy greens. And in 2015 and 2016, 19 people in nine states became ill with listeriosis after eating packaged leafy greens; all were hospitalized, and one person died.

The safest move is to stick with leafy greens that you cook. “If you cook greens until they are fully wilted, they’re likely to have been heated enough to be safe,” Rogers says. That step is most important for people especially vulnerable to listeria infections.

“Leafy greens are extremely nutritious,” Rogers says. “So unless there’s an ongoing, known outbreak, for most people the nutritional benefits outweigh the potential contamination risks.”

You might also be able to prevent listeria infections by eating leafy greens soon after you buy them, before bacteria has a chance to multiply, Thesmar says. “If someone is susceptible [to listeria infection], they’re going to have a much lower dose with a fresher product than later in the shelf life,” she says.

Finally, avoiding raw greens at restaurants may also help protect against foodborne illness: 85 percent of outbreaks linked to greens stemmed from restaurant meals, according to a 2015 CDC study.

source: https://www.consumerreports.org/food-safety/leafy-greens-with-listeria-sold-at-major-supermarkets/

© 2019 US Food Safety Corporation. No copyright claim is made for portions of this blog and linked items that are works of the United States Government, state governments or third parties.

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