Comparative Validation Study to Demonstrate the Equivalence of an Alternate Next-Day Enrichment Protocol for VIP® Gold for Salmonella Method to Culture Methods for the Detection of Salmonella in Selected Foods and Environmental Surfaces.

Background: VIP® Gold for Salmonella is a lateral flow immunodetection device that was validated by AOAC in 1999 as Official Method of Analysis 999.09. It was improved upon in 2009 by introducing gold colloid as the detection method. Objective: A simple next-day enrichment protocol using modified enterohemorrhagic Escherichia coli media was developed for the VIP Gold for Salmonella to improve the time-to-results and laboratory work flow. Methods: We tested 128 Salmonella strains, representing all serotypes from A to Z and 51 to 66 as well as 50 non-Salmonella strains for inclusivity/exclusivity. Performance of the VIP using the new enrichment protocol was compared with the U.S. Department of Agriculture (USDA) Microbiology Laboratory Guidebook reference culture procedure for the detection of Salmonella in ready-to-eat poultry, roast beef, and chicken carcass rinsate. VIP performance was also compared with the U.S. Food and Drug Administration (FDA) Bacteriological Analytical Manual (BAM) for the detection of Salmonella from raw spinach, raw almonds, raw pasta, and environmental surfaces (stainless steel, rubber, and plastic). Results: The VIP detected all 128 of Salmonella strains and none of the 50 non-Salmonella strains. There was no statistically significant difference in the numbers of positive results with VIP Gold for Salmonella protocol compared with appropriate USDA-Food Safety and Inspection Service or FDA-BAM reference methods for any of these matrixes. Conclusions: This new enrichment protocol has met all the requirements to be approved as a Performance Tested MethodSM. Highlights: The new enrichment protocol will improve the time-to-results and allow quicker decisions about the contamination of food products.

Comparative Validation Study to Demonstrate the Equivalence of an Alternate Next-Day Enrichment Protocol for the TRANSIA® PLATE Salmonella Gold Method to Culture Methods for the Detection of Salmonella in Selected Foods and Environmental Surfaces.

TRANSIA® PLATE Salmonella Gold is an ELISA that was validated by Association Française de Normalisation (AFNOR) in 2001 and as a Performance Tested MethodSM (PTM) by AOAC in 2006 (PTM No. 010602) as a two-step enrichment protocol requiring 48 h. A simple next-day enrichment protocol using modified Enterohemorrhagic Escherichia coli media was developed for the TRANSIA PLATE Salmonella Gold to improve the time-to-results and laboratory work flow. We tested 128 Salmonella strains, representing all serotypes from A though Z and 51-66. TRANSIA PLATE Salmonella Gold detected all 128 of these strains. None of the 50 non-Salmonella strains were detected by TRANSIA PLATE Salmonella Gold. Performance of TRANSIA PLATE Salmonella Gold using the new enrichment protocol was compared with U.S. Department of Agriculture Microbiology Laboratory Guidebook reference culture procedure for the detection of Salmonella in ready-to-eat poultry, ready-to-eat beef, and chicken carcass rinsate. In addition, TRANSIA PLATE Salmonella Gold performance was compared with U.S. Food and Drug Administration (FDA) Bacteriological Analytical Manual (BAM) for the detection of Salmonella from raw spinach, raw almonds, raw pasta, and environmental surfaces (stainless steel, rubber, and plastic). There was no statistically significant difference in the numbers of positive results TRANSIA PLATE Salmonella Gold protocol compared with the appropriate U.S. Department of Agriculture Food Safety and Inspection Service or FDA-BAM reference methods for any of these matrixes. Robustness testing demonstrated that the introduction of small changes in the normal assay parameters had no impact on the method performance. This new enrichment protocol has been approved as a Third Level modification to Performance Tested Method 010602.

Comparison of Assurance GDS(®) MPX ID for Top STEC with Reference Culture Methods for the Detection of E. coli Top 6 STEC; Direct Confirmation of Top 6 STEC from Isolation Plates and Determination of Equivalence of PickPen(®) and FSIS OctoMACS™ Concentration Protocols.

Assurance GDS(®) MPX ID for Top Shiga toxin-producing Escherichia coli (STEC; MPX ID) was validated according to the AOAC INTERNATIONAL Methods Committee Guidelines for Validation of Microbiological Methods for Foods and Environmental Surfaces as (1) a secondary screening method for specific detection of the Top 6 STEC serogroups (O26, O45, O103, O111, O121, and O145) in raw beef trim, raw ground beef, raw spinach, and on stainless steel; and (2) as a confirmatory method for the identification of pure culture isolates as Top 6 STEC. MPX ID is used in conjunction with the upfront BCS Assurance GDS MPX Top 7 STEC assay. This Performance Tested Method(SM) validation has two main parts: Method Developer studies and the Independent Laboratory study. A total of 180 samples and controls were analyzed. Results showed that MPX ID had no statistically significant differences with the reference culture methods for the detection of Top 6 STEC in the food matrixes (raw beef trim, raw ground beef, and raw spinach) and environmental sponges (stainless steel) studied. Inclusivity/exclusivity studies were also conducted. One hundred percent inclusivity among the 50 Top 6 STEC serovars tested and 100% exclusivity for the 30 non-Top 6 STEC organisms tested were demonstrated. For validation of MPX ID as a confirmatory method for isolated colonies, all inclusivity and exclusivity organisms were streaked for isolation onto five STEC plating media: modified rainbow agar, Levine's eosin-methylene blue (L-EMB) agar, rainbow agar with novobiocin and cefixime, and enterohemolysin agar with selective agents as well as trypticase soy agar with yeast extract. These isolated colonies were suspended and analyzed by Assurance GDS MPX Top 7 STEC and MPX ID. MPX ID was able to correctly confirm all inclusivity organisms from all plate types, except two STEC isolates from L-EMB agar plates only in the Independent Laboratory study. All exclusivity organisms were correctly determined by MPX ID as non-Top 6 STEC from the STEC plating media. An additional but separate part of these studies was a comparison of immunomagnetic separation (IMS) efficiency using the Assurance GDS procedure with a PickPen(®) device and the U.S. Department of Agriculture procedure using the OctoMACS™ Separator device for plating onto chromogenic agar. Results demonstrated the equivalence of the two IMS procedures for plate confirmation of Top 7 STEC.