Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 26, 2006
Publication Date: December 20, 2006
Citation: Nou, X., Arthur, T.M., Bosilevac, J.M., Harhay, D.M., Guerini, M.N., Kalchayanand, N., Koohmaraie, M. 2006. Improvement of immunomagnetic separation for Escherichia coli O157:H7 detection by the pickpen magnetic particle separation device. Journal of Food Protection 69:2870-2874. Interpretive Summary: Detection of bacterial pathogens from food- or animal-related samples has been based on methods using antibodies attached to beads to capture bacteria. The antibodies bind a specific target, such as a bacterial cell, and the beads are magnetic so they are attracted to another magnetic device that holds the beads in place while non-target bacteria are washed away. Traditional methods for isolating bacteria-magnetic bead complexes from samples are labor intensive and can have poor sensitivity for the target organism due to high numbers of non-target bacteria that are not effectively washed away during the process. This report compares the conventional method of magnetic bead recovery to a new procedure using a magnetic particle recovery device, called PickPen. The target for the majority of these studies is Escherichia coli O157:H7 in various types of samples including cattle feces, hides, carcasses, and ground beef. Comparison of the two magnetic separation methods showed the PickPen method to be better at detecting E. coli O157:H7 from cattle carcass surface, cattle hide, and cattle fecal samples. No significant improvement in detection was observed when isolating bacteria from ground beef samples. The use of PickPen greatly increases the number of samples one can process without adversely affecting recovery of target bacteria and improves detection of E. coli O157:H7 in most sample types.
Technical Abstract: Conventional immunomagnetic separation (IMS) procedures, which use an external magnetic source to capture magnetic particles against the side of a test tube, are labor intensive and can have poor sensitivity for the target organism due to high background microflora that is not effectively washed away during the IMS process. This report compares the conventional IMS procedure to a new IMS procedure using an intra-solution magnetic particle transfer device, the PickPen (BioNobile, Turku, Finland). The IMS target for the majority of these studies is Escherichia coli O157:H7 in various types of samples including cattle feces, hides, carcasses, and ground beef. Comparison of the two IMS methods showed significant difference (P < 0.05) in the efficiency of detecting E. coli O157:H7 from cattle carcass surface, cattle hide, and cattle fecal samples. No significant improvement (P > 0.05) in E. coli O157:H7 detection was observed when PickPen IMS procedure was used to isolate this pathogen from ground beef samples. The use of PickPen IMS greatly increases the throughput of the IMS procedure and may be more compatible with various emerging technologies for pathogen detection. In addition, the efficacy of sequential IMS for multiple pathogens is reported herein.