ARS | Publication request: Escherichia coli O157 and other Shiga toxin producting E. coli: detection by immunomagnetic particle-based assays

Submitted to: Encyclopedia of Food Microbiology
Publication Type: Book / Chapter
Publication Acceptance Date: June 1, 2012
Publication Date: N/A

Technical Abstract: Shiga toxin-producing Escherichia coli (STEC), including E. coli O157:H7 and non-O157 STEC cause hemorrhagic colitis and hemolytic uremic syndrome and are important food-borne pathogens that can contaminate various types of food. The USDA Food Safety and Inspection Service declared E. coli O157:H7 as an adulterant in beef in 1994, and in 2011 the FSIS declared the top six non-O157 STEC as adulterants. Thus, sensitive methods are essential for detection and isolation of these pathogens in food and other types of complex samples that generally contain a large number of background microorganisms. One technique that has simplified testing for these pathogens is immunomagnetic separation (IMS), which involves the use of magnetic beads coated with antibodies against the pathogens to concentrate the target organisms and remove food matrix particles and background microflora. IMS followed by plating onto selective and differential agars, or by rapid techniques such as PCR, ELISA, electrochemiluminescence, flow cytometry, or microscopy markedly enhances the speed and sensitivity of assays for detection of E. coli O157:H7 and non-O157 STEC. Enrichment culturing times can be reduced, thus the entire assay can potentially be performed in 8 h or less. IMS may be useful for the recovery of stressed, sublethally injured STEC, which are not resuscitated during selective enrichment culturing. Specificity is determined by the antibody bound to the beads, thus with the availability of appropriate antisera, improved assay systems for detection of E. coli O157:H7, non-O157 STEC, as well as other bacterial pathogens can be developed. The IMS technique is easy to perform, does not require elaborate instrumentation, and can easily be applied to isolation, concentration, and detection of pathogens in food and other types of samples.