ARS | Publication request: Applications of Immunomagnetic Capture and Time-Resolved Fluorescence Detection for Salmonella Enteritidis in Liquid Eggs

Submitted to: Optical Engineering
Publication Type: Proceedings
Publication Acceptance Date: March 31, 2008
Publication Date: May 22, 2008
Citation: Tu, S., Gehring, A.G., Paoli, G. 2008. Applications of Immunomagnetic Capture and Time-Resolved Fluorescence Detection for Salmonella Enteritidis in Liquid Eggs. International Society of Optical Engineering (SPIE).6983:1-5 . Optical Engineering.

Technical Abstract: An immuno sandwich method was evaluated for the detection of Salmonella in liquid eggs. Liquid eggs spiked with different out-break strains of Salmonella were mixed with proper enrichment media and incubated at 37 C for 4 to 20 h. After enrichment, immunomagnetic beads (IMB) coated with anti Salmonella antibodies were used to capture the bacteria. Samarium (Sm) labeled anti Salmonella antibodies were then used to form sandwiched complexes with IMB captured bacteria. Sandwiched Salmonella were then treated with Sm-chelator to allow the measurement of the released Sm by time-resolved fluorescence (TRF). The processes ranging from IMB capture to Sm chelation were performed using an automated KingFisher apparatus. With this approach, the presence of ~ 1 CFU of outbreak strains of Salmonella Enteritidis per egg (~50 g of liquid eggs) could be detected after enrichment for 20 h at 37 C. For higher levels of Salmonella Enteritidis contamination, e.g., 10 CFU per 50 g of liquid eggs, the enrichment time could be reduced to 5 h at 37 C. The results demonstrated that a combination of IMB capture and TRF measurement could be a rapid and sensitive method for Salmonella Enteritidis detection in liquid eggs.