ASSAY OF SALMONELLA IN ENRICHMENT CULTURES OF FOODS, FEEDS AND ENVIRONMENTAL-SAMPLES BY THE POLYMYXIN-CLOTH ENZYME-IMMUNOASSAY

A variety of foods, animal feeds and environmental samples were analyz ed for the presence of Salmonella using the polymyxin-cloth enzyme imm unoassay (p-CEIA) system. Salmonella lipopolysaccharide (LPS) antigens were captured from test samples on polymyxin-coated polyester cloth, followed by immunoenzymatic detection of bound antigens using a monocl onal antibody recognizing an LPS common core oligosaccharide. Dairy an d egg products, animal feeds and environmental samples from food proce ssing plants were pre-enriched for 24 h, followed by selective enrichm ent for a further 24 h in either tetrathionate brilliant green (TBG), selenite cystine (SC) or brain-heart infusion broth containing 0.5% ye ast extract, 0.5% cholate and 0.3% selenite (BYCS). The samples were a ssayed by the p-CEIA after each stage of enrichment. After selective e nrichment, the p-CEIA gave results which were in complete agreement wi th the standard culture technique in the analysis of air feuds examine d. On the other hand, a combination of selective enrichment and the p- CEIA out-performed the Modified Semi-Solid Rappaport Vassiliadis (MSRV ) method in screening pre-enrichment cultures of feeds and environment al samples. Use of the new selective medium BYCS prior to performing t he p-CEIA gave the highest recovery of Salmonella from feeds and envir onmental samples. (C) 1997 Elsevier Science B.V.