Category Archives: Microbiology Investigations

FDA

The US Food and Drug Administration (FDA), along with Centers for Disease Control and Prevention (CDC) as well as state and local partners, investigated an outbreak of Listeria monocytogenes infections linked to enoki mushrooms. FDA identified enoki mushrooms distributed by Utopia Foods, Inc. of Glendale, New York, and imported from China, and enoki mushrooms labeled as “Producer: Shandong Youhe Biotechnology, Co.,” with an address in China and “Distributed By: Sun Hong Foods, Inc.” as likely sources of illnesses in this outbreak. Enoki mushrooms are long thin white mushrooms, usually sold in clusters. They are especially popular in East Asian cuisine and are also known as enokitake, golden needle mushrooms, futu, seafood mushrooms, or lily mushrooms.

As of April 7, 2023, CDC reports this outbreak is over. Five people in four states (CA, MI, NJ, NV) were sickened with five people reporting hospitalization. There was one pregnancy-associated illness and no reported deaths.

During this investigation, FDA leveraged ongoing surveillance sampling efforts. Several import and retail samples were collected and tested by FDA and/or state and local partners. Laboratory results indicated that many enoki products sampled were contaminated with Listeria. On January 17, 2023, FDA reported a positive import sample of enoki mushrooms that matched both outbreak strains and resulted in a voluntary recall expansion from Utopia Foods, Inc.

Additional sample collection and analysis conducted by the Maryland Department of Health identified both outbreak strains of Listeria in two product samples of enoki mushrooms. The products that tested positive were sold in a 7.05-oz (200g) clear plastic package with a brown and green label and included a label on the back of the package that states: “Producer: Shandong Youhe Biotechnology Co.,” with an address in China, and “Distributed By: Sun Hong Foods, Inc.”

While the outbreak has ended, FDA continues to assess the risk of Listeria contamination in enoki mushrooms.

Further, FDA has added enoki mushrooms from China to a country wide import alert (Import Alert (IA) #25-21). As stated in the Import Alert, FDA Import Divisions may subject shipments of enoki mushrooms from Republic of Korea and China to Detention Without Physical Examination (DWPE). FDA import alerts inform the FDA’s field staff and the public that the agency has enough evidence to allow for DWPE of products that appear to be in violation of the FDA’s laws and regulations. DWPE helps to prevent potentially violative products from being distributed in the United States.

In addition, after the 2020 outbreak linked to enoki mushrooms, FDA began implementing a Strategy to Help Prevent Listeriosis and Salmonellosis Outbreaks Associated with Imported Enoki and Imported Wood Ear Mushrooms, to protect public health. This prevention strategy is an affirmative, deliberate approach undertaken by FDA and stakeholders to help limit or prevent future outbreaks linked to certain FDA-regulated foods.

Recommendation

Although this outbreak investigation has ended, FDA and CDC are working to better understand the risk of Listeria monocytogenes contamination in enoki mushrooms.

CDC and FDA advise people who are pregnant, aged 65 or older, or have a weakened immune system to cook enoki mushrooms thoroughly, and to: 

• Avoid eating enoki mushrooms raw. 
• Keep raw enoki mushrooms separate from foods that won’t be cooked.
• Wash your hands, items, and surfaces that have touched raw enoki mushrooms.

Restaurants should cook enoki mushrooms thoroughly before serving to customers, follow FDA’s safe handling and cleaning advice, and use extra vigilance in cleaning and sanitizing any surfaces and containers that may have come in contact with these products.

This advice is based on the following information:

• Two recent multistate Listeria outbreaks have been linked to enoki mushrooms: This outbreak, and the first known Listeria outbreak in the United States linked to enoki mushrooms in 2020.
• During this investigation, FDA leveraged ongoing surveillance sampling efforts. Several import and retail samples were collected and tested by FDA and/or state and local partners and many were contaminated with Listeria. Some samples contained high levels of the bacteria.
• More than 20 recalls of enoki mushrooms due to potential Listeria contamination have been conducted since 2020.