Evaluation of fecal dna purification methods for the detection of E. coli O157:H7 in feces of naturally infected feedlot cattle.
[FIGURE 1 OMITTED]
Using conventional culture methods (gold standard), 456 fecal samples were analyzed for detectable levels of E. coli O157:H7. QIAamp Kit was used to purify fecal DNA (from enrichment and non-enrichment feces) and E. coli O157:H7 genes (Stx1 and Stx 2) were targeted and amplified by PCR.
A total of 199/456 (43.6%) fecal samples were positive for E. coli O157:H7 by culture. Of the 456 enrichment fecal samples, E. coli O157:H7 Shiga toxin-like genes were detected from 159/456 (34.6%) enrichment fecal samples compared to 43/456 (9.4%) targeted from non-enrichment samples. There was a substantial agreement (Kappa > 0.61) between the gold standard and QIAamp Kit (enrichment) as opposed to a fair agreement (Kappa > 0.21) for non-enrichment samples. Positive agreement rates were greater for the enrichment samples (83.6%) compared to the non-enrichment samples (65%). Agreement rates were lower (86.4%) for QIAamp Kit for enrichment samples compared to non-enrichment samples (98.5%). These data indicate that the use of QIAamp DNA Stool Mini Kit as the select protocol for E. coli O157:H7 detection in cattle feces should take into account the respective accuracy of the test for enriched and non-enriched fecal samples in comparison to the conventional culture method.
Acknowledgments: We are grateful to USDA-APHIS (Agrosecurity: Disease Surveillance and Public Health) and USDA-CSREES (Food Safety Risk Assessment Grant) for providing funding for this project.
1. Khaitsa, M. L., M. L. Bauer, P. S Gibbs, G. P Lardy, D. K. Doetkott, and R. B. Kegode. 2005. Comparison of two sampling methods for Escherichia coli O157:H7 detection in feedlot cattle. J. Food Prot. 68:1724-1728.
2. Gioffre, A., L. Meichtri, M. Zumarraga, R. Rodriguez, and A. Cataldi. 2004. Evaluation of QIAamp DNA stool purification kit for Shiga-toxigenic Escherichia coli detection in bovine fecal swabs by PCR. Revista Argentina de Microbiologia. 36:1-5.
Ebot S. Tabe *, James Oloya, Dawn K. Doetkott, Margaret L. Khaitsa.
* The Great Plains Institute of Food Safety, North Dakota State University, Fargo, N D 58105. Department
of Veterinary and Microbiological Sciences, North Dakota State University, 1523 Centennial Blvd,
Fargo, ND 58105
|Printer friendly Cite/link Email Feedback|
|Author:||Tabe, Ebot S.; Oloya, James; Doetkott, Dawn K.; Khaitsa, Margaret L.|
|Publication:||Proceedings of the North Dakota Academy of Science|
|Date:||Apr 1, 2008|
|Previous Article:||Characterizing the growth of escherichia coli O157:H7 on the surface of beef.|
|Next Article:||Podocyte loss in aging OVE26 transgenic diabetic mice.|