FDA has released a report on the multiagency investigation of a Salmonella Typhimurium outbreak associated with packaged salad greens grown in a controlled environment agriculture (CEA) operation. The outbreak, which occurred between June and August 2021, resulted in 31 reported illnesses and four hospitalizations. It is also believed to be the first of its kind associated with leafy greens grown in a CEA facility.

No “conclusive” root cause was found, but the FDA did pinpoint the outbreak strain of Salmonella to a stormwater retention basin located next to the CEA farm. The investigation did not, however, find that this was the definitive source of contamination of the leafy greens. The agency also identified certain conditions, factors and practices that could lead to contamination, including the pond water used, growth media storage methods, water management practices and overall sanitation practices.

In the report, the FDA listed eight requirements and recommendations that apply to hydroponic facilities using CEA, including implementing effective sanitation procedures and sampling plans, conducting pre- and post-harvest sampling and testing of food, water and the physical environment, implementing procedures that are effective in rapidly cooling and cold-holding harvested leafy greens after harvest, and ensuring all growing pond water is safe and of sanitary quality.

The eight-page Investigation Report: Factors Potentially Contributing to the Contamination of Packaged Leafy Greens Implicated in the Outbreak of Salmonella Typhimurium During the Summer of 2021 is available on FDA’s website.