Rapid and Specific Detection of Escherichia coli O157:H7 in Ground Beef Using Immunomagnetic Separation Combined with Loop-Mediated Isothermal Amplification
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Publication date: 2018-06-30
Pol. J. Food Nutr. Sci. 2018;68(2):115–123
Escherichia coli O157:H7 is well known for many foodborne outbreaks that lead to fatal infections in human being worldwide. The objective of this study was to develop a rapid and sensitive method for detection of EHEC O157:H7 from ground beef using a method that combined immunomagnetic separation (IMS) with loop-mediated isothermal amplification (LAMP). The EHEC O157:H7 cells were separated with Dynabeads coated with anti-EHEC O157:H7 after a short enrichment for 4 h. Then, EHEC O157:H7 was identified by LAMP assay for amplifying and detecting the rfbE gene, which is highly conserved in all EHEC O157:H7 strains and exhibits strain-specific gene expression. The LAMP method results analyzed with real time turbidity measurements showed a high specificity and sensitivity, with a positive detection rate of amplification of EHEC O157:H7 DNA diluted to a minimum equivalent concentration of 1.8 × 101 CFU/mL, which was 10 times more sensitive than the conventional PCR assay. The IMS followed with LAMP could capture and detect a bacterial concentration as low as 3×101 CFU/mL from the meat samples, which was close to the sensitivity of LAMP assay with pure culture. IMS combined with realistic LAMP method is a simple, rapid, highly specific gene amplification technology that is suitable for implementing as a screening assay in basic laboratory and field test for detecting food contamination.
An evaluation of immunomagnetic separation-real-time PCR (IMS-RTiPCR) combined assay for rapid and specific detection of Escherichia coli O157:H7 in raw milk and ground beef
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