Purpose: RAPID’Salmonella is a chromogenic media for detection of Salmonella spp. in food based on two simultaneous enzymatic activities, identification of Salmonella spp. by C8-esterase activity and differentiation from other enterobacteria by β-glucosidase activity. The media was granted AOAC Performance Tested Method Status (# 050701) in May of 2007. A modification of the method has been tested using a single shortened (18h) enrichment time in buffered peptone water supplemented with a mix of selective agents.
Methods: In a method comparison study, the test method was compared to the US Department of Agriculture Food Safety and Inspection Service Microbiology Laboratory Guidebook (USDA MLG) reference method for the analysis of chicken raw ground chicken and to the US Food and Drug Administration Bacteriological Analytical Manual (FDA BAM) reference method for the analysis of eggs, cantaloupe and peanut butter. One hundred Salmonella strains were tested in an inclusivity study and 31 non-target organisms were tested in an exclusivity study.
Results: Method comparison results demonstrated there was no significant difference in the performance of the RAPID’Salmonella method when compared to the appropriate reference method. Inclusivity and exclusivity rates were 97% and 90%, respectively.
Significance: The method presented greatly shortens the time to a Salmonella result by eliminating the need for a secondary enrichment step. By utilizing a chromogenic color change reaction to identify Salmonella, colonies can be selected more easily and with greater confidence so action can be taken on potentially contaminated food.