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

• Main Authors: Birce MERCANOGLU TABAN, Sait Aykut AYTAC
• Format: Article
• Language: English
• Published: Sociedade Brasileira de Ciência e Tecnologia de Alimentos
• Series: Food Science and Technology
• Subjects: Escherichia coli 0157:H7; immunomagnetic separation; milk; raw ground beef; real-time PCR
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0101-20612019005011102&lng=en&tlng=en

Abstract The aim of this study is to optimize a rapid and specific method for detection of E. coli O157:H7 (EHEC) from food samples with high background flora using an immunomagnetic separation-real-time polymerase chain reaction assay (IMS-RTiPCR). For this, EHEC cells were recovered from raw milk and ground meat samples that were artificially contaminated to the final concentrations of 101, 103 and 105 cfu EHEC/mL or g, after a non-selective pre-enrichment at 35 °C for 8 h following either with or without capturing by micro-sized beads. Then, EHEC cells were identified by RTiPCR. The study was also carried out without any enrichment to evaluate the enrichment efficiency of the assay. By comparing the assay with and without pre-enrichment, we showed that even the usage of specific micro-sized beads did not improve EHEC detection in raw milk and ground beef samples and so gave false negative results unless an 8-h pre-enrichment was applied. Besides, the assay can be completed in less than 9 h with a minimum detection limit of 103 cfu EHEC/mL or g in foods and hence was found to be simple routine-based method that exhibits great potential for implementing as a rapid screening of EHEC in microbial tests as compared to existing techniques.