Assurance® Enzyme Immunoassay Eight Hour Method for Detection of Enterohemorrhagic Escherichia coli O157:H7 in Raw and Cooked Beef (Modification of AOAC Official Method 996.10): Collaborative Study

Abstract

AOAC Official Method 996.10, Assurance® Enzyme Immunoassay (EIA) for Escherichia coli O157:H7 (EHEC), was modified to incorporate a new enrichment protocol using BioControl EHEC8™ medium for testing raw and cooked beef. Foods were tested by EIA and the U.S. Department of Agriculture/Food Safety and Inspection Service (USDA/FSIS) enrichment conditions and the FDA Bacteriological Analytical Manual (BAM) isolation and confirmation techniques. A total of 14 collaborators participated. Raw and cooked ground beef were inoculated with E. coli O157:H7 at 2 different levels: a high level where predominantly positive results were expected, and a low level where fractional recovery was anticipated. Collaborators tested 378 test portions and controls by both the 8 h EIA and the USDA/FSIS enrichment methods, for a total of 756 test portions. Of the 378 paired test portions, 75 were positive and 212 were negative by both methods. Thirteen test portions were presumptively positive by EIA and could not be confirmed culturally; 30 were negative by EIA, but confirmed positive by culture; and 65 were negative by the culture method, but confirmed positive by the EIA method. There was no statistical difference between results obtained with the Assurance EIA for EHEC 8 h method and the culture method for raw ground beef. The Assurance EIA had a significantly higher recovery for cooked beef.

Rapid laboratory identification and characterization of verocytotoxigenic (Shiga toxin producing) Escherichia coli (VTEC/STEC)

“…However, there should nowadays be no excuse for a reasonably sized hospital, veterinary or food laboratory not to be able to detect the presence of any VTEC in specimens. Methods such as those recently published (Feldsine et al. 2002a,b), which only rely on the detection of VTEC O157 and not on the other VTEC, perpetuate the false myth of the uniqueness of this serotype.…”

Rapid methods for the detection of foodborne bacterial pathogens: principles, applications, advantages and limitations

“…The Assurance EIA test kits for Salmonella, Escherichia coli , O157:H7, Listeria monocytogenes , and Campylobacter are currently available (Fung, 2002 ). Assurance EIA test kit for the detection of Escherichia coli O157:H7 in raw and cooked beef was used in the study conducted by Feldsine et al ( 2002 ). Besides, Stewart et al ( 2001 ) performed the detection of Salmonella in alfalfa sprouts by Assurance EIA test kit and Taha et al ( 2010 ) performed the detection of Salmonella in chicken meat by Assurance EIA test kit.…”