Simultaneous Detection of Escherichia coli O157:H7 and Salmonella Typhimurium: The Use of Magnetic Beads Conjugated with Multiple Capture Antibodies

Abstract

Streptavidin-coated magnetic beads were conjugated with biotinylated capture antibodies to both Escherichia coli O157:H7 and Salmonella Typhimurium to form multipathogen capture immunomagnetic beads (IMB-M). The efficacy of these beads was investigated in both pure and mixed culture suspensions, as well as in inoculated spinach and ground beef. Using dual-label time-resolved fluorescence, a sandwich immunoassay consisting of europium-and samarium-labeled detection antibodies was used to measure the capture of E. coli and Salmonella, respectively. IMB-M was just as effective as the mixture of IMB against E. coli and Salmonella in capturing both organisms in pure culture and E. coli in mixed culture. Capture of Salmonella in mixed culture by IMB-M resulted in lower fluorescent signals, but comparable detection limit. In inoculated food samples, IMB-M was just as effective as the mixture of IMB specific for both target organisms in detecting 1 cfu/g of E. coli and 100 cfu/g of Salmonella after a 6-h enrichment at 37°C. Multi-pathogen capture IMB have the potential to be convenient and important tools for multi-pathogen detection.

Highly specific fiber optic immunosensor coupled with immunomagnetic separation for detection of low levels of Listeria monocytogenes and L. ivanovii

“…Antibodies are routinely used as affinity ligands to separate and concentrate the target analyte from sample matrices using paramagnetic beads (PMBs) [31-34] and also as recognition or reporter molecules on immunoassay platforms [31,35,36]. The PMB-captured cells may be presumptively identified by plating them on selective or differential media [37], or their identity may be confirmed by PCR [38,39], flow cytometry [40], or cytotoxicity assay [41].…”

“…The PMB-captured cells may be presumptively identified by plating them on selective or differential media [37], or their identity may be confirmed by PCR [38,39], flow cytometry [40], or cytotoxicity assay [41]. The use of a biosensor to detect cells captured by immunomagnetic separation (IMS) is an attractive approach due to increased speed, accuracy, and detection of a low number of targets [34,42,43]. …”

Simultaneous detection ofSalmonella enterica,Escherichia coliandListeria monocytogenesin food using a light scattering sensor

“…Simultaneous multipathogen detection capability on a single-assay platform is highly desirable and economically advantageous since it can reduce the bench space required for handling a large number of samples, as well as supplies, reagents and labour, thus lowering the potential overall cost of testing each pathogen (Bhunia 2014;Huntington et al 2018). For multipathogen detection, several methods are proposed such as mPCR (Bhagwat 2003;Mukhopadhyay and Mukhopadhyay 2007;Settanni and Corsetti 2007;Kawasaki et al 2010), array-based immunosorbent assays (Chen and Durst 2006) and antibody-based array biosensor techniques (Taylor et al 2006;Tu et al 2011;Gehring et al 2012Gehring et al , 2013Gehring et al , 2015Ohk and Bhunia 2013). Therefore, our goal was to investigate if BARDOT could be used to detect and distinguish the three major foodborne pathogens, S. enterica, STEC including E. coli O157:H7 and Listeria species from food since these three are considered the leading causes of foodborne diseases in the United States (Scallan et al 2011).…”