Microbiology Methods for ERP Review 3-2020

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Evaluation of the Solus One Salmonella Assay in Select Foods: Collaborative Study First Action 2020.XX Benjamin Bastin, M. Joseph Benzinger, Jr., Erin S. Crowley and James Agin Q Laboratories, 1930 Radcliff Drive, Cincinnati, OH 45204 Ray Wakefield Solus Scientific Solutions, Ltd., 9 Mansfield Network Centre, Millennium Business Park, Concorde Way, Mansfield, Nottinghamshire NG19 7JZ, United Kingdom Collaborators: J. Picket, K. Kensel, R. Prince, J. Reynolds, K. Sysoukrath, T. Krueger, J. Steenstra, L. Thompson-Strehlow, N. Clemens, M. Del Rosario Quezada, I. O’Mahony, Y. Wood, O. Van der Merwe, A. Dagutat, M. Maartens, B. Centrella, S. Pendleton, J. Dyzel The Solus One Salmonella immunoassay utilizes Salmonella specific selective media and automated liquid handling, for the rapid and specific detection of Salmonella species in select food types. The candidate method was evaluated using 375 g test portions in an unpaired study design for a single matrix, instant non-fat dry milk (NFDM) powder. The matrix was compared to the United States Food and Drug Administration/ Bacteriological Analytical Manual (FDA/BAM) Chapter 5 Salmonella reference method. Fourteen (14) participants from 12 laboratories, including academia and industry, located within the United States, Mexico, South Africa, Germany and the United Kingdom were solicited for the collaborative study. Three levels of contamination were evaluated for each matrix: an uninoculated control level (0 colony forming units (CFU)/test portion) , a low inoculum level (0.2-2 CFU/test portion) and a high inoculum level (2-5 CFU/test portion). Statistical analysis was conducted according to the Probability of Detection (POD) statistical model. Results obtained for the low inoculum level test portions produced a dLPOD value with 95% confidence interval of 0.08, (-0.11, 0.18). The dLPOD results indicate equivalence between the candidate method and reference method for the matrix evaluated and the method demonstrated acceptable inter-laboratory reproducibility as determined in the collaborative evaluation. False positive and false negative rates were determined for the matrix and produce values of <2%. Based on the data generated, the method demonstrated acceptable inter-laboratory reproducibility data and statistical analysis. ___________________________________________________________________________ Low moisture foods typically do not support the growth of Salmonella ; however, studies have indicated that the organism can remain viable for extended periods of time. In fact, Salmonella does not need to propagate to cause illness, infections can occur with products contaminated with as low as 1 CFU/g [1]. While rare, Salmonella outbreaks associated with low-moisture products often impact large numbers of people. [1]. Over the last few decades, several low-moisture product outbreaks have occurred involving chocolate, raw almonds, dry seasonings, pet food and peanut butter [1]. Typically, Salmonella are sensitive to heat processing; however, these organisms can become resistant as the water activity of a product becomes lower [2]. Manufacturers have to ensure that

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