E. coli O157:H7 Outbreak Linked to RTE Salads; Multi-Agency Investigation Under Way
By Heidi Parsons
The U.S. Centers for Disease Control and Prevention (CDC) on Nov. 10 announced that it is collaborating with public health officials in California, Washington, and Arizona; the U.S. Department of Agriculture’s Food Safety and Inspection Service (USDA-FSIS); and the U.S. Food and Drug Administration (FDA) to investigate a multistate outbreak of Shiga toxin-producing Escherichia coli O157:H7 (STEC O157:H7) infections. The infections have been linked to ready-to-eat (RTE) salads produced by Glass Onion Catering, a business of RIchmond, CA-based Atherstone Foods. On Nov. 10, the company voluntarily recalled certain prepackaged salads retailed by Trader Joe's and Walgreen's, as well as two bulk-packed salads retailed by Whole Foods Markets.
A total of 26 individuals infected with the outbreak strain of STEC O157:H7 have been reported from three states. The number of ill persons identified in each state is as follows: Arizona (1), California (22), and Washington (3).
Among persons for whom information is available, illness onset dates range from Sept. 29, 2013 to Oct. 26, 2013. Ill persons range in age from 4 years to 78 years, with a median age of 28 years. Sixty-one percent of ill persons are female. Among 21 persons with available information, 6 (28%) reported being hospitalized. Two ill persons have developed HUS, and no deaths have been reported.
Public health investigators are using DNA "fingerprints" of E. coli bacteria obtained through diagnostic testing with pulsed-field gel electrophoresis, or PFGE, to identify cases of illness that could be part of this outbreak. They are using data from PulseNet, the national subtyping network made up of state and local public health laboratories and federal food regulatory laboratories that performs molecular surveillance of foodborne infections.
The type of bacteria responsible for this outbreak is among those referred to as Shiga toxin-producing E. coli, or STEC. Some types of STEC frequently cause severe disease, including bloody diarrhea and hemolytic uremic syndrome (HUS), which is a type of kidney failure. STEC bacteria are divided into serogroups (e.g., O157 or O121). E. Coli O157 is the STEC serogroup found most commonly in U.S. patients. The STEC O157:H7 PFGE pattern in this outbreak is new to the PulseNet database. It has never been seen before.
Epidemiologic and traceback investigations conducted by officials in local, state, and federal public health, agriculture, and regulatory agencies indicate that two ready-to-eat salads, Field Fresh Chopped Salad with Grilled Chicken and Mexicali Salad with Chili Lime Chicken, produced by Glass Onion Catering and sold at Trader Joe’s grocery store locations, are one likely source of this outbreak of STEC O157:H7 infections.
On Nov. 10, 2013, Glass Onion Catering voluntarily recalled approximately 181,620 pounds of ready-to-eat salads and sandwich wrap products with fully cooked chicken and ham that may be contaminated with STEC O157:H7. The products were produced between Sept. 23, 2013 and Nov. 6, 2013 and shipped to distribution centers intended for retail sale in Arizona, California, Nevada, New Mexico, Oregon, Texas, Utah and Washington.
The products subject to recall are regulated by both FSIS and FDA. Products regulated by FSIS bear the establishment number “P-34221” inside the USDA mark of inspection.