Major retailers including Whole Foods Market and Costco were among those wher Consumer Reports found leafy greens contaminated with the potentially deadly bacterium Listeria monocytogenes.

The pre-eminent consumer watchdog group gathered 284 samples of fresh leafy greens and tested them for the pathogen, according to a statement from the organization. Six of the samples, purchased by Consumer Reports at grocery store chains including Acme, Costco, Hannaford, and Whole Foods tested positive for Listeria monocytogenes.

“All of the greens were purchased between June 3 and June 19, 2019, in Connecticut, New Jersey, and New York,” according to the organization’s statement. 

“. . . 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.”

Officials from Consumer Reports immediately informed the Food and Drug Administration and the retailers about the test results. The organization statement reports that the FDA initiated inspections of the implicated production plant.

The other products that tested positive for Listeria monocytogenes, and the stores wher they were purchased, were:

• 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.

Of the samples that were contaminated with the pathogen, two 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, according to Consumer Reports.

“While we found listeria, we did not find (certain) other bacteria that cause foodborne illness, such as Salmonella and E. coli O157:H7 in any of the 284 samples we tested,” the organization reported. 

The consumer advocacy group stressed that the public “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,” said James. E. Rogers, director of food safety research and testing at Consumer Reports.

“The safest thing is to stick with greens you can cook.”

about Listeria infections
Food contaminated with Listeria monocytogenes may not look or smell spoiled but can still cause serious and sometimes life-threatening infections. Anyone who has eaten food suspected to be contaminated with the pathogen and developed symptoms of listeriosis infection should seek medical treatment and tell their doctors about the possible Listeria exposure.

It can take up to 70 days after exposure to Listeria for symptoms of listeriosis to develop. 

Symptoms of Listeria infection can include vomiting, nausea, persistent fever, muscle aches, severe headache and neck stiffness. Specific laboratory tests are required to diagnose Listeria infections, which can mimic other illnesses. 

Pregnant women, the elderly, young children, and people such as cancer patients who have weakened immune systems are particularly at risk of serious illnesses, life-threatening infections and other complications. Although infected pregnant women may experience only mild, flu-like symptoms, their infections can lead to premature delivery, infection of the newborn or even stillbirth.