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United States Department of Agriculture

Agricultural Research Service

Title: Evaluation of Culture and Pcr-Based Detection Methods for Escherichia Coli O157:h7 in Inoculated Ground Beef

Authors
item Arthur, Terrance
item Bosilevac, Joseph
item Nou, Xiangwu
item Koohmaraie, Mohammad

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 6, 2005
Publication Date: August 20, 2005
Citation: Arthur, T.M., Bosilevac, J.M., Nou, X., Koohmaraie, M. 2005. Evaluation of culture- and PCR-based detection methods for Escherichia coli O157:H7 in inoculated ground beef. Journal of Food Protection. 68:1566-1574.

Interpretive Summary: E. coli O157:H7 is a foodborne pathogen of significant concern to the beef processing industry. Several steps have been implemented to eliminate contamination of ground beef. These systems have been shown to be very effective; however contamination with E. coli O157:H7 can still occur. Currently, the meat industry has developed test-and-hold programs to prevent release of contaminated product. In such programs each lot of product must be tested for E. coli O157:H7 and if the results are found to be negative the product can be released into commerce. Optimization of three testing attributes, detection time, specificity, and sensitivity, are critical to the success of such programs. Since ground beef is a highly perishable product, the testing methodology used must be as rapid as possible. Also, the test must have a low false positive rate so product is not needlessly discarded. Finally, false negatives cannot be tolerated. False negative results would allow contaminated product to be released and potentially cause disease. In this study commercially developed methods for detecting E. coli O157:H7 in ground beef were compared for their abilities to meet the above criteria. In weighing all three factors, the DNA-based detection systems were all found to have comparable performance. There are slight advantages for each system, but nothing that firmly placed one system over the others. The culture-based systems had slightly higher sensitivity, but the detection times (24 to 48 h) were at least 12 h longer than those of the DNA-based methods (8 to 12 h).

Technical Abstract: E. coli O157:H7 is a foodborne pathogen of significant concern to the beef processing industry. This pathogen is characterized by a low infective dose and ability to cause severe disease. Several antimicrobial intervention technologies have been implemented to eliminate contamination of ground beef. These systems have been shown to be very effective; however contamination with E. coli O157:H7 can still occur. Currently several beef processors employ test-and-hold systems for increased quality control of ground beef. In such programs each lot of product must be tested for E. coli O157:H7 and the results found to be negative prior to release of the product into commerce. Optimization of three testing attributes, detection time, specificity, and sensitivity, are critical to the success of such strategies. Since ground beef is a highly perishable product, the testing methodology used must be as rapid as possible. Also, the test must have a low false positive rate so product is not needlessly discarded. Finally, false negatives cannot be tolerated. False negative results would allow contaminated product to be released and potentially cause disease. In this study culture-based and PCR-based commercially developed methods for detecting E. coli O157:H7 in ground beef were compared for their abilities to meet the above criteria. In weighing all three factors, the PCR-based systems were all found to have comparable performance. There are slight advantages for each system, but nothing that firmly placed one system over the others. The culture-based systems had slightly higher sensitivity, but the detection times (24 to 48 h) were at least 12 h longer than those of the PCR-based methods (8 to 12 h).

Last Modified: 8/1/2014
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