Collaborative ring-trial of Dynabeads(R) anti-Salmonella for immunomagnetic separation of stressed Salmonella cells from herbs and spices

Eight laboratories participated in a Salmonella detection ring-trial which compared selective enrichment by conventional broths with immunomagnetic separation (IMS) using Dynabeads(R) Anti-Salmonella. Laboratories analyzed six types of herbs and spices that were spiked with one of six freeze-dried Salmonella species. Each herb and spice analysis comprised of 12 samples (25 g each) which had been spiked at three different levels, plus a negative control and stored for one week prior to testing. Out of a total 468 samples analyzed, 195 (41.7%) were positive by both methods. Eighteen samples were positive only by IMS enrichment, in comparison with 19 positive samples by conventional enrichment broths and not IMS. These results confirm the potential use of IMS as an alternative to enrichment broths for Salmonella isolation.