Detection of Escherichia coli O157:H7 Using Immuno Beads

摘要

A new fluorescent sandwich method for the detection of Escherichia coli O157:H7 was developed. Strepavidin coated magnetic beads and fluorescence beads reacted with biotinylated anti E. coli O157 antibodies to form the immuno magnetic beads (IMB) and immuno fluorescence beads (IFB), respectively. The E. coli bacteria captured by IMB were further labeled with IFB to form IMB_M-(E. coli O157:H7)_N-IFB_O sandwich complexes where the subscripts M, N and O were integral numbers. Using broth cultured E. coli O157:H7, the sandwich method was able to detect the bacteria at the level of ～ 10~3 to 10~4 CFU/mL. Known quantity of freshly cultured E. coli O157:H7 cells were added to ground beef obtained from local markets. The bacteria in inoculated beef patties were enriched in EC broth containing novobiocin. After enriched for 4 h at 40℃, the developed IMB-IFB method was applied to detect the presence of E. coli O157:H7. The results demonstrated that the developed method could detect the presence of 1 CFU of E. coli O157:H7 per gram of ground beef.