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United States Department of Agriculture

Agricultural Research Service

Title: Research Note: Screening Bovine Carcass Sponge Samples for Escherichia Colio157 Using a Short Enrichment Coupled with Immunomagnetic Separation and a Pcr-Based (Bax(r)) Detection Step

item Kang, Dong Hyun
item Gallagher, Genevieve
item Koohmaraie, Mohammad
item Siragusa, Gregory

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 26, 2001
Publication Date: N/A

Interpretive Summary: Escherichia coli O157:H7 has emerged as a foodborne pathogen of major public health concern in the United States and may cause severe disease and death in humans. The presence of very low levels of the bacteria in consumed ground beef has been associated with disease. U.S. Department of Agriculture Food Safety Inspection Service (FSIS) regulations declare that the presence of E. coli O157:H7 in ground beef at very low levels constitutes adulterated and dangerous product that must not be distributed. Consequently, highly sensitive and reliable methods for the detection of E. coli O157:H7 are critical to ensure food safety. A commercially available kit (BAX[R][registered trademark] system) based on DNA detection substantially shortens the length of time required to identify a sample containing E. coli O157:H7 when compared to standard culture methods. The accuracy of the BAX(R) system was compared to a conventional culture method for screening E. coli O157 from bovine carcass sponge samples. There was a high correlation between the results obtained using the BAX(R) system and those obtained using the culture method. Therefore, the BAX(R) system is an effective, simple, and rapid method for detection of E. coli O157 in bovine carcass sponge samples.

Technical Abstract: The recently modified BAX(R)(registered trademark) system for detection of enterohemorrhagic Escherichia coli O157:H7 in food samples was compared to a culture method for detection of the organism in carcass sponge samples. Enriched samples were subjected to immunomagnetic separation; the bead suspension was divided and plated on selected media or stored at minus 20 deg C, then subjected to BAX(R) analysis. The results showed a high degree of agreement between the plating method and the BAX(R) system. Fifty-two of the 59 culture-positive samples were also positive using the BAX(R) system (88.1% agreement). Of the 76 samples that appeared negative for the presence of E. coli O157:H7 by the culture method, 66 were determined as negative using the BAX(R) system (86.8 % agreement). Interestingly, four of the 10 samples found negative by the culture method and positive by the BAX(R) method were culture-positive upon further analysis. Based on these data, the BAX(R) system is a rapid, reliable, and simple method to screen for E. coli O157:H7 in carcass sponge samples.

Last Modified: 4/22/2015
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