The purpose of this study was to evaluate an enzyme-linked immunosorbent assay (ELISA) and an immunoblot procedure for detection and isolation of Shiga toxin-producing Escherichia coli (STEC) from beef, and to correlate the presence of STEC in beef with E. coli and total coliform counts. A total of 120 samples of boneless beef supplied to a meat processor in southern Ontario were tested for the presence of STEC, E. coli, and total coliforms. Following enrichment in modified tryptic soy broth, samples were screened for Shiga toxin (Stx) by a Stx-ELISA and a Vero cell assay (VCA). Samples that were positive in the Stx-ELISA were subjected to the Stx-immunoblot for STEC isolation. Overall, 33.3% of samples were positive in the VCA, and 34.2% were positive in the Stx-ELISA. There was almost complete agreement between the Stx-ELISA and the VCA results (kappa = 0.98). The sensitivity and specificity of the Stx-ELISA with respect to the VCA were 100% and 98.75%, respectively. STEC were isolated by the Stx-immunoblot from 87.8% of the samples that were positive in the Stx-ELISA. The STEC isolates belonged to 19 serotypes, with serotype O113:H21 accounting for 10 of 41 isolates. No STEC of serotype O157:H7 were isolated. There was a significant correlation between E. coli counts and total coliform counts (Spearman correlation coefficient = 0.68, P < 0.01). The E. coli count was positively correlated with detection of STEC by both the Stx-ELISA and the VCA (P < 0.01).
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Research Article|
September 01 2000
Use of a Shiga Toxin (Stx)-Enzyme-Linked Immunosorbent Assay and Immunoblot for Detection and Isolation of Stx-Producing Escherichia coli from Naturally Contaminated Beef
HEBA NASHED ATALLA;
HEBA NASHED ATALLA
1Department of Pathobiology, University of Guelph, Guelph, Ontario
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ROGER JOHNSON;
ROGER JOHNSON
2Laboratory of Foodborne Zoonoses, Health Canada, Guelph, Ontario N1G 3W4
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SCOTT MCEWEN;
SCOTT MCEWEN
3Department of Population Medicine, University of Guelph, Guelph, Ontario, Canada
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R. W. USBORNE;
R. W. USBORNE
1Department of Pathobiology, University of Guelph, Guelph, Ontario
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C. L. GYLES
C. L. GYLES
*
1Department of Pathobiology, University of Guelph, Guelph, Ontario
* Author for correspondence. Tel: 519-824-4120; Fax: 519-767-0809; E-mail: cgyles@ovc.uoguelph.ca.
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J Food Prot (2000) 63 (9): 1167–1172.
Article history
Received:
February 16 2000
Accepted:
April 24 2000
Citation
HEBA NASHED ATALLA, ROGER JOHNSON, SCOTT MCEWEN, R. W. USBORNE, C. L. GYLES; Use of a Shiga Toxin (Stx)-Enzyme-Linked Immunosorbent Assay and Immunoblot for Detection and Isolation of Stx-Producing Escherichia coli from Naturally Contaminated Beef. J Food Prot 1 September 2000; 63 (9): 1167–1172. doi: https://doi.org/10.4315/0362-028X-63.9.1167
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