Title: Methods for detection, isolation, and identification of Non-O157 shiga toxin-producing Escherichia coli Authors
Submitted to: United States Japan Natural Resources Protein Panel
Publication Type: Proceedings
Publication Acceptance Date: October 17, 2012
Publication Date: December 8, 2012
Citation: Fratamico, P.M., Wasilenko, J.L., Medina, M.B., Sommers, C.H. 2012. Methods for detection, isolation, and identification of Non-O157 shiga toxin-producing Escherichia coli. United States Japan Natural Resources Protein Panel. MA. Technical Abstract: Non-O157 Shiga toxin producing E. coli (STEC) have been increasingly associated with human infections in the U.S. and worldwide, and it is estimated that in the U.S. non-O157 STEC cause more than twice the number of infections overall compared to STEC O157:H7. The Centers for Disease Control and Prevention identified non-O157 STEC serogroups O26, O45, O103, O111, O121, and O145 as the “top six” most prevalent serogroups associated with illness. Cattle and other ruminants are the main reservoirs for STEC, and food of bovine origin is an important vehicle of STEC infection. Research in our laboratory has focused on the analysis of STEC virulence and development of methods for detection and isolation of these pathogens. A method developed in collaboration with the USDA Food Safety and Inspection Service (FSIS) that is used in their verification sampling program to test for STEC in beef samples collected from federally inspected establishments and retail stores is described in the FSIS Microbiological Laboratory Guidebook (MLG 5B.03). In addition, a collaboration with industry resulted in the production of antibodies against non-O157 STEC, and they were used for developing immunomagnetic separation and latex reagents for isolation of the top six non-O157 STEC. Finally, a collaboration with industry resulted in the development of non-O157 STEC rapid testing kits (BAX System Real-Time Suite of PCR assays for STEC) that are currently commercially available. A series of method comparison studies were conducted to compare the BAX System to the MLG method, and results were comparable. The test kits were used in a survey of retail ground beef to detect the presence of Salmonella, STEC O157:H7, and the top six non-O157 STEC. Out of a total of 308 ground beef samples tested, STEC O103 and O157:H7 strains were isolated each from two separate naturally contaminated samples, and Salmonella was isolated from 27 samples. The methods and reagents developed for non-O157 STEC and can be used by the food industry and regulatory agencies for testing beef and potentially other foods for STEC serogroups that are important food-borne pathogens worldwide.