Detection of Salmonella Enteriditis from Egg Components Using Different Immunomagnetic Beads and Time-resolved Fluorescence

Abstract

The types of chemical linkage used to bind antibodies to magnetic beads to form immunomagnetic beads (IMB) were compared in the capture and detection of Salmonella Enteriditis from egg white, egg yolk, and whole egg. Egg components were inoculated with outbreak strains of S. Enteriditis. After incubation under different conditions, IMBs derived from linking antibodies to core magnetic beads via biotin-streptavidin interactions, Schiffbase bonds and unspecified proprietary chemistry were used to capture S. Enteriditis. Europium-labeled antiSalmonella antibodies completed the sandwich, and timeresolved fluorescence served as the means of detection. For the Salmonella isolated in stationary phase and cultured from universal pre-enrichment broth (UPB), the detection signal intensity was affected by the chemistry utilized to link the antibodies to IMB, with results varying among the three test strains. When S. Enteriditis was cultured in egg yolk alone, plating data were similar to those of the growth of S. Enteriditis in UPB. Egg white by itself did not support the growth of S. Enteriditis. The addition of UPB to egg white restored the growth of Salmonella and yielded stronger detection signals than from cultures obtained from UPB with egg yolk. The detection signals obtained from the immunoassay were less intense for cultures grown in egg yolk + UPB than from cultures grown in UPB alone. The lower detection signals elicited by all IMBs suggest the availability of the antigenic groups recognized by the antibodies on IMBs was reduced in the presence of egg yolk.

Salmonella and Tomatoes

“…For bulky, fibrous, or otherwise difficult to filter produce material, this is a less than optimal approach. Recently, advances in the use of immunomagnetic beads have improved the sensitivity and reliability of detection (Tu et al, 2008).…”

“…This type of magnetic collection allows for flow-through collection of a large volume of material, and is a significant improvement over older methods that relied on centrifugation to concentrate and collect the immunoattractant material. As the primary basis for the recognition and capture is based on the immunoattraction of the bead surface, this technology can be adapted for a range of purposes, such as concentrating pathogens such as Salmonella (Tu et al, 2008), and in detecting non-O157 Shiga toxin-producing E. coli in a variety of foods (Wang et al, 2013). This technology can also be used to concentrate and analyze chemical contaminants of interest, such as toxins and adulterants (Gessler et al, 2006).…”

Advanced Technologies for Detection and Elimination of Bacterial Pathogens

“…Recently, advances in the use of immunomagnetic beads have improved the sensitivity and reliability of detection (Tu et al, 2008). Air and water sampling has traditionally used flow-through filtration, with analysis of the filter membrane as the diagnostic step.…”

“…As the primary basis for the recognition and capture is based on the immunoattraction of the bead surface, this technology can be adapted for a range of purposes, such as concentrating pathogens such as Salmonella (Tu et al, 2008), and in detecting non-O157 Shiga toxin-producing E. coli in a variety of foods (Wang et al, 2013). These micron-sized beads are surface treated with antibodies that are specific to the pathogen of interest.…”

Advanced Technologies for Detection and Elimination of Pathogens

“…In addition to concentrating pathogens such as Salmonella (Tu et al, 2008), this technology can be used to concentrate and analyze chemical contaminants of interest, such as toxins and adulterants (Gessler et al, 2006). These micron-sized beads are surface-treated with antibodies that are specific to the pathogen of interest.…”