THE DETECTION OF SALMONELLA IN SKIMMED-MILK POWDER ENRICHMENTS USING CONVENTIONAL METHODS AND IMMUNOMAGNETIC SEPARATION

Skimmed milk powders were spiked with one of three Salmonella serovars and incubated in buffered peptone water for 24 h. No false-negative r esults were obtained by immunomagnetic separation (IMS), compared to s even for selenite cysteine, one for Muller-Kauffmann tetrathionate and two for Rappaport-Vassiliadis enrichment broths. Salmonella virchow w as detected and enumerated during the pre-enrichment incubation by IMS and indirect conductance techniques. The Saint. virchow cell number d id not increase after 12 h incubation and remained at 3 x 10(6) cfu ml (-1). IMS was able to capture Salm. virchow cells at cell numbers ca 5 0 ml(-1) in the presence of a 1000 greater number of non-salmonella ce lls.