Detection of immunomagnetically captured Escherichia coli O157:H7 by antibody-conjugated alkaline phosphatase.
A rapid and sensitive detection process for Escherichia coli O157:H7 was developed using alkaline phosphatase (APase)-labeled anti-E. coli O157 antibodies to tag the targeted bacteria. Immunomagnetic beads or antibody-labeled streptavidin-coated magnetic beads were then used to capture the APase-tagged E. coli. Immunomagnetically captured bacteria were washed and distributed into microplates or optical cuvettes. The enzyme-catalyzed hydrolysis of p-nitro-phenol phosphate in alkaline solutions was then followed. Less than 1000 cfu/ml of E. coli O157:H7 could be detected. This approach was applied to detect the bacteria artificially spiked in beef hamburgers. Less than 1 cfu/g of E. coli O157:H7 produced a significant response after cultural enrichment for 4-6 h at 37 degrees C.
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United States Department of Agriculture, Eastern Regional Research Center, Wyndmoor, PA 19038, USA.
Patterson
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D
Briggs
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Irwin
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Yu
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D000469:Alkaline Phosphatase / Q000378:metabolism*; D000818:Animals; D000906:Antibodies / Q000276:immunology / Q000378:metabolism*; D002417:Cattle; D019453:Escherichia coli O157 / Q000254:growth & development / Q000276:immunology* / Q000302:isolation & purification*; D005516:Food Microbiology; D007124:Immunoenzyme Techniques / Q000379:methods*; D018189:Immunomagnetic Separation / Q000379:methods*; D008460:Meat / Q000382:microbiology*; D012680:Sensitivity and Specificity; D013997:Time Factors
D000906:Antibodies; D000469:Alkaline Phosphatase