Automated immunomagnetic separation and microarray detection of E-coli O157 : H7 from poultry carcass rinse

We describe the development and application of an electromagnetic flow cell and fluidics system for automated immunomagnetic separation (IMS) of Esche richia coli O157:H7 directly from poultry carcass rinse. We further describ e the biochemical coupling of automated sample preparation with nucleic aci d microarrays. Both the cell concentration system and microarray detection method did not require cell growth or enrichment from the poultry carcass r inse prior to IMS. Highly porous Ni foam was used to enhance the magnetic f ield gradient within the flow path, providing a mechanism for immobilizing immunomagnetic particles throughout the fluid rather than the tubing wall. A maximum of 32% recovery efficiency of non-pathogenic E. coli was achieved within the automated system with 6 s cell contact times using commercially available antibodies targeted against the O and K antigens. A 15-min proto col (from sample injection though elution) provided a cell recovery efficie ncy that was statistically similar to >1 It batch captures. O157:H7 cells w ere reproducibly isolated directly from poultry carcass rinse with 39% reco very efficiency at 10(3) CFU ml(-1) inoculum. Direct plating of washed bead s showed positive recovery of O157:H7 directly from poultry carcass rinse a t an inoculum. of 10 CFU ml Recovered beads were used for direct polymerase chain reaction (PCR) amplification and microarray detection, with a proces s-level detection limit (automated cell concentration though microarray det ection) of <10(3) CFU ml(-1) in poultry carcass rinse. (C) 2001 Elsevier Sc ience B.V. All rights reserved.