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United States Department of Agriculture

Agricultural Research Service


item Wijey, Chandi
item Crawford, Claude
item Tu, Shu I
item Paoli, George

Submitted to: Journal of Rapid Methods and Automation in Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/23/2004
Publication Date: 8/1/2004
Citation: Wijey, C., Crawford, C.G., Tu, S., Paoli, G. Effect of bacterial protein extraction reagent and sodium azide on the detection of escherichia coli 0157:h7 using immunomagnetic-electrochemiluminescence. Journal of Rapid Methods and Automation in Microbiology. 2004. 12. pp. 115-126.

Interpretive Summary: Escherichia coli O157:H7 is a food-borne pathogen that causes severe gastroenteritis. Additionally, E. coli O157:H7 is the leading cause of hemolytic uremic syndrome (HUS), a kidney disease that is potentially fatal, particularly in children and immunocompromised individuals. Consumption of undercooked ground beef is the most common cause of E. coli O157:H7 infection in humans. To improve the detection of E. coli O157:H7 in ground beef, a more rapid and sensitive method was developed for the analysis of E. coli O157:H7 in ground beef using an immunomagnetic separation (IMS)/ electrochemiluminescent (ECL) procedure. Treatment of ground beef enrichment samples with 80% B-PER, a commercially available bacterial cell lysis reagent, and 0.5% sodium azide decreased the culturable bacteria in the samples below detectable levels, increased the sensitivity of the ECL detection 4-5 fold, and decreased the assay time by eliminating the need for heat treatment and filtration steps. This modified procedure is an appealing alternative to heat treatment during sample preparation prior to ECL detection of food-borne pathogens. This assay can be recommended as an excellent E. coli O157:H7 screening method for use by the food industry.

Technical Abstract: Immunomagnetic capture combined with electrochemiluminescent detection (IM-ECL) is a rapid and sensitive method for the detection of pathogenic microorganisms from food. Prior to ECL detection enrichment samples are often heated to reduce the viability of pathogens. In this work, a number of cell-lysis reagents and biocides were examined as alternatives to the heat treatment step to decrease bacterial viability in enrichment sample as well as to improve the IM-ECL detection of Escherichia coli O157:H7. A combination of Bacterial Protein Extraction Reagent (B-PER), a non-ionic detergent, and sodium azide (NaN3) decreased bacterial viability in ground beef enrichments and significantly increased the sensitivity of IM-ECL detection of E. coli O157:H7.

Last Modified: 10/19/2017
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