The CDC, FDA, USDA and health officials in several states investigated a multi state outbreak of Shiga toxin-producing E. coli O157 infections linked to Costco Rotisserie Chicken Salad. The outbreak was concentrated mostly in the western United States. Nineteen outbreak associated case patients were reported from seven states. Three people were hospitalized. Two developed hemolytic uremic syndrome. No deaths were reported. Among people for whom information was available, illnesses started on dates ranging from October 6, 2015 to November 3, 2015.

Epidemiologic evidence collected during the investigation suggested that rotisserie chicken salad made and sold in Costco Wholesale stores in several states was the likely source of this outbreak. On November 20, 2015 Costco voluntarily removed all remaining rotisserie chicken salad from all stores in the US. On November 26, 2016 Taylor Farms Pacific Inc., voluntarily recalled the celery onion diced blend used in the Costco chicken salad. The FDA conducted a traceback investigation of the FDA regulated ingredients used in the chicken salad to try to determine which ingredient was linked to illness. However, the traceback investigation did not identify a common source of contamination.

The outbreak was assigned CDC Cluster ID number 1511MTEXH-1.