Salmonella detection in foods and feeds in 27 hours by an enzyme immunoassay

A heterogeneous enzyme immunoassay (EIA), which could be completed within 27 h, was developed for the detection of salmonellae in foods. Samples were subjected to the usual non-selective enrichment for 16–18 at 35°C and to a short (6 h) post-enrichment in a moderately selective broth. The EIA was carried out on polystyrene microtitration plates. A pooled polyvalent Salmonella flagellar antiserum and a protein A-alkaline phosphatase conjugate were used. The sensitivity of the enzyme immunoassay compared favorably with that of the conventional cultural technique for detection of Salmonella in 40 naturally contaminated food and feed samples. No sample was positive only by the cultural technique; samples positive only by the enzyme immunoassay were observed for feeds. Some specimens yielded high background values indicating possible interference from food proteins.