AOAC-RI ERP Book MICRO Sept 2016.pdf

OMAMAN-08/Collaborative Study Protocol March 2014 Expert Review Panel Use Only

3M Petrifilm SALX Collaborative Study

July 2013

OMA-2013-July-XXX

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INTRODUCTION

1.0

The goal of this collaborative study is to estimate the following performance parameters of the 3M™ Petrifilm™ Salmonella Express (SALX) System: probability of detection (POD) and the difference in the POD at 3 contamination levels for both the candidate and reference methods. Test portions from 3 different contamination levels, including negative controls, will be sent to collaborators where they will perform the 3M Petrifilm SALX method along with the corresponding reference method. Raw fresh ground beef will be tested at 25g and dry dog

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food will be tested at 375g.

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Description of the 3M Petrifilm SALX Method

The 3M Petrifilm SALX method is intended for the rapid and specific detection and biochemical confirmation of Salmonella from food and food process environmental samples after enrichment in 3M™ Salmonella Enrichment Base with the added 3M™ Salmonella Enrichment Supplement. The 3M™ Petrifilm™ Salmonella Express Plate is a s ia mple ready-to-use chromogenic culture medium system that contains a cold-water- soluble gelling agent and is selective and differential for Salmonella, providing a presumptive result in as little as 44 hours from low microbial background foods (≤10 4 cfu/g), and 52 hours from high microbial background foods (≥10 4 cfu/g). The 3M™ Petrifilm™ Salmonella Express Confirmation Disk contains a biochemical substrate that

facilitates the biochemical confirmation of Salmonella organisms

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Summary of PTM/Precollaborative Study

The 3M Petrifilm SALX method was validated according to AOAC Guidelines (2002) in a harmonized PTM/OMA study. The aim of this study was to demonstrate that the 3M Petrifilm SALX method could detect Salmonella in select foods as claimed by the

manufacturer.

The 3M Petrifilm Salmonella Express System was evaluated following the AOAC Performance Tested Methods requirements: inclusivity/exclusivity, ruggedness, stability/lot to lot consistency and method comparison. The 3M Petrifilm SALX method was compared to the USDA/FSIS-MLG 4.05 Isolation and Identification of Salmonella from Meat, Poultry, Pasteurized Egg and Catfish Products for raw ground chicken, pasteurized liquid whole egg, raw ground beef, raw ground pork, and cooked chicken nuggets and to FDA/BAM Chapter 5 Salmonella for frozen uncooked shrimp, fresh

AOAC Research Institute Expert Review Panel Use Only

bunched spinach, dry dog food, and stainless steel.

Overall the assay was equivalent to the reference methods based on the Chi square test for significant difference and the Probability of Detection (POD). There were

no unexpected results in all of the other PTM requirements.

The 3M Petrifilm Salmonella Express System is sufficiently rugged to withstand small variations in the experimental parameters of enrichment incubation time and temperature, plate incubation time and temperature, disk incubation time and temperature and various plate hydration options. Each parameter was tested using both the high and low microbial load methods as described in the Instructions

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