Rapid and multiplexed quantification of Salmonella, Escherichia coli O157:H7, and Shigella flexneri in ground beef using flow cytometry.

ABSTRACT

Salmonella, Escherichia coli O157H7 (E. coli O157H7) and Shigella flexneri (S. flexneri) might contaminate similar types of meat products and cause deadly diseases in humans. In reality, ground beef samples may carry more than one pathogen and a rapid and accurate detection method for the simultaneous identification of multiple specific pathogenic strains in ground beef is crucial. In this study, a sample pretreatment protocol and a flow cytometry method were developed for rapid and multiplexed quantification of the three pathogens without cultural enrichment in ground beef. The whole process of sample pretreatment, staining, and instrument analysis can be accomplished within 1 h. The three bacteria upon sample pretreatment were demonstrated good recoveries (93.8%-101.2%). The quantitative detection range of the mothed was 103 to 108 cells/g for all three pathogens, and the detection limit for Salmonella, E. coli O157H7 and S. flexneri in ground beef were 3.1 × 103 cells/g, 2.1 × 103 cells/g and 2.3 × 103 cells/g, respectively. Therefore, the as-developed approach is a rapid and quantitative method for multiplexed detection of Salmonella, E. coli O157H7, and S. flexneri in ground beef.