Contamination of foods with pathogens such as Escherichia coli O157:H7 and Salmonella is a major concern worldwide and rapid, sensitive, and reliable methods are needed for detection of these organisms. Since these pathogens can contaminate similar foods and other types of samples, a multiplex polymerase chain reduction (PCR) was designed to allow simultaneous detection of both E. coli O157:H7 and Salmonella spp directly from enrichment cultures. Samples of apple cider, beef carcass wash water, ground beef, and bovine feces were inoculated with both E. coli O157:H7 and S. typhimurium at various bacterial levels. Following enrichment culturing for 20–24 h at 37°C in modified EC broth or buffered peptone water both containing novobiocin, the samples were subjected to a DNA extraction technique or to immunomagnetic separation then tested by the multiplex PCR assay. Four pairs of primers were employed in the PCR: primers for amplification of E. coli O157:H7 eaeA, stx 1/2 and plasmid sequences and for amplification of a portion of the Salmonella invA gene. Four fragments of the expected sizes were amplified in a single reaction and visualized following agarose gel electrophoresis in all the samples inoculated with ≤ 1 CFU g−1 or ml−1. Results can be obtained in approximately 30 h. The multiplex PCR is a potentially powerful technique for rapid and sensitive co-detection of both pathogens in foods and other types of samples.
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Received 28 December 1997/ Accepted in revised form 19 March 1998
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Fratamico, P., Strobaugh, T. Simultaneous detection of Salmonella spp and Escherichia coli O157:H7 by multiplex PCR. J Ind Microbiol Biotech 21, 92–98 (1998). https://doi.org/10.1038/sj.jim.2900520
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DOI: https://doi.org/10.1038/sj.jim.2900520