Comparison of Salmonella Bio-EnzaBead Immunoassay Method and Conventional Culture Procedure for Detection of Salmonella in Foods

Abstract

A rapid enzyme immunoassay screening procedure (EIA) utilizing two monoclonal antibodies specific for salmonellac was compared to the standard culture method (BAM/AOAC) on 1,289 samples representing 26 food types. The samples consisted of 760 artificially inoculated, 150 naturally contaminated, and 379 uninoculated food samples. There were 594 samples positive by the EIA (optical densities greater than 0.2 at 405 nm), of which 568 were confirmed culturally from M-broth. A total of 570 samples was positive by the BAM/AOAC procedure. Of the foods tested, there was no significant difference between the two methods, with the exception of cake mix and raw shrimp. The EIA was significantly better for detecting Salmonella in cake mix, while the culture procedure was more productive for shrimp. The method employed a 24 ± 2-h preen-richment, an 18-h selective enrichment, and a 6-h M-broth post-enrichment. The EIA assay required an additional 2 h for a total of 48 h, compared to a minimum of 4 d by BAM/AOAC.