The FDA has closed its investigation into an outbreak of Listeria monocytogenes infections traced to supplemental shakes served in medical facilities. A total of 42 people were sickened in the outbreak, with 14 deaths reported.

The Food and Drug Administration said in its final outbreak update that all 42 of the patients had required hospitalization. The agency, with the Centers for Disease Control and Prevention, had been investigating the outbreak since Nov. 25, 2024. By the end of the outbreak, patients in 21 states had been identified. According to the CDC, the recent investigation showed the outbreak dates back to 2018.

The source of the Listeria was traced to Lyons ReadyCare brand and Sysco Imperial brand frozen supplemental shakes manufactured by Prairie Farms from the Prairie Farms Dairy facility in Fort Wayne, IN.

The FDA’s traceback investigation identified that each of the long-term care facilities who supplied invoice information for review from 2024 to present received frozen supplemental shakes of either Lyons ReadyCare or Sysco Imperial brand.

As part of the investigation, the FDA conducted an onsite inspection and collected environmental and product samples at Prairie Farms Dairy Inc. in Fort Wayne, IN. Three of the environmental swabs collected from the processing area tested positive for Listeria monocytogenes. Whole Genome Sequencing analysis determined that the Listeria detected in the samples was the strain of Listeria that caused illnesses in the outbreak.

In response to the outbreak investigation, L...