DETECTION OF SALMONELLA FROM RAW FOOD SAMPLES USING DYNABEADS(R) ANTI-SALMONELLA AND A CONVENTIONAL REFERENCE METHOD

A Dynal core method has been established using Dynabeads(R) anti-Salmo nella to detect Salmonella from all categories of food samples. The pr otocol consists of the standard pre-enrichment of samples in buffered peptone water followed by immunomagnetic separation and subsequent sel ective enrichment of the bead-bacteria complexes in Rappaport-Vassilia dis Soya Peptone broth before plating onto Salmonella selective media. This modified IMS cultural method is intended to replace or augment t raditional cultural methods used for Salmonella detection due to its s pecificity and increased sensitivity. The optional direct plating of b ead-bacteria complexes onto solid media using a swab-streak technique is suitable for processed foods or samples known to have a history of very low resident flora. In an evaluation using 100 naturally contamin ated samples, this IMS core method detected 39 of the 44 positive samp les detected by all the methods combined, compared to 31 detected by t he conventional ISO 6579 reference method. Furthermore, in ten differe nt food matrices inoculated with low levels (1-5 cells/25 g) of twenty Salmonella serovariants, frozen for one month before being examined, the IMS core method, showed a 90% concordance with the ISO method and isolated two more Salmonella positive samples than the conventional IS O method. (C) 1997 Elsevier Science B.V.