4. AOACRIMicroMethods-2018Awards

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FOOD BIOLOGICAL CONTAMINANTS

Evaluation of VIDAS ® UP Listeria Assay (LPT) for the Detection of Listeria in a Variety of Foods and Environmental Surfaces: First Action 2013.10 E rin C rowley , P atrick B ird , J onathan F lannery , M. J oseph B enzinger , J r , K iel F isher , M egan B oyle , T ravis H uffman , B en B astin , P aige B edinghaus , W illiam J udd , T hao H oang , J ames A gin , and D avid G oins Q Laboratories, Inc., 1400 Harrison Ave, Cincinnati, OH 45214 R onald L. J ohnson 1 bioMérieux, Inc., 595 Anglum Rd, Hazelwood, MO 63042 Collaborators: A. Bollenbacher; B. Brahmanda; R. Burkhart; J. Cannon; A. Capps; L. Cesanas; D. Davis; D. Ebbing; H. Elgaali; B. Hand; R. Hiles; J. Hirsch; B. Howard; J. Jolly; S. Joseph; A. Kehres; K. Klemms; J. Li; B. May; M. Michels; J. Mills; S. Moore; N. Nagassar; S. Owusu; N. Palen; L. Parker; B. Paul; B. Perry; J. Pickett, N. Rogman; G. Rosario; P. Rule; C. Said; M. Sala-Rhatigan; A. Stegmann; T. Stubblefield; K. Wiggins; J. Zimmerman

Submitted for publication November 1, 2013. The method was approved by the Expert Review Panel for Microbiology Methods for Feed and Environmental Surfaces as First Action. The Expert Review Panel for Microbiology Methods for Feed and Environmental Surfaces invites method users to provide feedback on the First Action methods. Feedback from method users will help verify that the methods are fit for purpose and are critical to gaining global recognition and acceptance of the methods. Comments can be sent directly to the corresponding author or methodfeedback@aoac.org. 1  Corresponding author’s e-mail: ron.johnson@biomerieux.com Supplemental data is available on the J. AOAC Int. website, http:// aoac.publisher.ingentaconnect.com/content/aoac/jaoac and follow link to supplemental data. DOI: 10.5740/jaoacint.13-372 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). For this evaluation, 1800 unpaired replicate test portions were analyzed by either the VIDAS LPT or AOAC 993.12. Each inoculation level was analyzed using the Probability of Detection (POD) statistical model. For the low-level inoculated test portions, difference in collaborator POD (dLPOD) values of 0.01, (–0.10, 0.13), with 95% confidence intervals, were obtained for both 25 and 125 g test portions. The range of the confidence intervals for dLPOD values for both the 25 and 125 g test 03/10/2019 The VIDAS ® UP Listeria (LPT) is an automated rapid screening enzyme phage-ligand based assay for the detection of Listeria species in human food products and environmental samples. The VIDAS LPT method was compared in a multi-laboratory collaborative study to AOAC Official Method 993.12 Listeria monocytogenes in Milk and Dairy Products reference method following current AOAC guidelines. A total of 14 laboratories participated, representing government and industry, throughout the United States. One matrix, queso fresco (soft Mexican cheese), was analyzed using two different test portion sizes, 25 and 125 g. Samples representing each test portion size were artificially contaminated with Listeria species at three levels, an uninoculated

portions contains the point 0.0 indicating no statistically significant difference in the number of positive samples detected between the VIDAS LPT and the AOAC methods. In addition to Oxford agar, VIDAS LPT test portions were confirmed using Agar Listeria Ottavani and Agosti (ALOA), a proprietary chromogenic agar for the identification and differentiation of L. monocytogenes and Listeria  species. No differences were observed between the two selective agars. The VIDAS LPT method, with the optional ALOA agar confirmation method, was adopted as Official First Action status for the detection of Listeria species in a variety of foods and environmental samples. T he current classification of the genus Listeria includes six well-characterized species, with L. monocytogenes being the species of most concern in foodborne outbreaks (1). Listeria species are short, non-spore forming Gram-positive rods that are ubiquitous in the environment and can be found in soil, decaying vegetation, and most environments (2). While the number of people who become ill from listeriosis, the disease caused by Listeria, is relatively small, the high mortality rate from infection makes it one of the leading causes of death from foodborne illness (2). Of primary concern for illness from Listeria outbreaks are the elderly, pregnant women, infants, and people with compromised immune systems (3). Outbreaks from Listeria have been linked to such foods as ready-to-eat deli meats, hot dogs, pâtés, dairy products, soft cheeses, smoked seafood, raw sprouts, and most recently cantaloupes (4). The VIDAS UP Listeria (LPT) assay, an automated enzyme phage- ligand based assay for the screening of Listeria in food and environmental samples, provides the ability to detect Listeria after only 26 h of enrichment. TheVIDASLPTassay uses a primary enrichment (prewarmed to 18–25°C) to detect Listeria species in 25 g test portions after 26–30 h of enrichment. For cantaloupe melons, whole melons are soaked in approximately 1 L LPT broth and incubated following conditions outlined for 25 g test portions. For larger