Polyclonal enzyme immunoassay method for detection of motile and non-motile Salmonella in foods: comparative study

A new enzyme immunoassay (EIA) method for detection of motile and non-motile Salmonella was examined in a comparative study. This method uses a proprietary formulation of polyclonal antibodies to Salmonella and is controlled to maintain specificity. Sensitivity is enhanced with an additional antibody reaction designed to minimize false-negative reactions attributable to steric interference that can occur during conjugate binding in immunoassay procedures. Twenty food types representative of a wide variety of food products were analyzed by both the EIA method and the AOAC/Bacteriological Analytical Manual (BAM) method, 967.26. Of the 1000 samples analyzed, there was a 95.6% agreement rate between the EIA method and the AOAC/BAM method. False-negative rates for the 2 methods were comparable for all foods and all Salmonella levels except ground poultry, where the EIA method detected significantly more confirmed positive samples than did the AOAC/BAM method. Twenty-seven samples were positive by EIA but negative by the culture method, and 17 samples were negative by EIA but positive by the culture method. There were no false-positive isolates detected in the comparative study.