Improvement of immunomagnetic separation for Escherichia coli O157:H7 detection by the PickPen magnetic particle separation device.

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 because of 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 with an intrasolution magnetic particle transfer device, the PickPen. 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 a 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 the PickPen IMS procedure was used to isolate this pathogen from ground beef samples. Use of the 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.