<p> Strategic Diagnostics Inc Technical Bulletin SELECT # 2 </p><p>Technical Bulletin </p><p>Comparison of the RapidChek® SELECT™ Salmonella System with Other Rapid Methods</p><p>Introduction: Aim: Salmonella is an important human pathogen, which has been implicated as a major cause of foodborne illness worldwide. To evaluate the performance of RapidChek® SELECT™ Each year, this organism is responsible for approximately for Salmonella as compared to the cultural reference method 1.4 million cases of illness in the United States, 95% of and other Rapid tests in the market, specificially, the Dupont which are contracted through foodborne transmission, 600 of BAX system and the BioMerieux VIDAS system. these typically result in death. Poultry has been identified as a leading reservoir for transmission. Various methods have been developed to allow reduction in time required for the Experimental Protocol: detection of the pathogen, as standard cultural methods for the detection of Salmonella in foods is time consuming and This study was designed to compare various competitive laborious requiring 4-5 days for a confirmed result. methods for the recovery and detection of Salmonella in raw Developing a method presents several difficulties, as poultry. In this study, raw ground turkey was inoculated Salmonella is a complex organism consisting of a large with either 0.3 or 1 CFU/25 g (based on enumeration by genre (over 2400 species), and it is closely related to several dilution plating) S. infantis ARS 22. Twenty-five (25) other bacteria including E. coli and Citrobacter, which samples of ground turkey inoculated at each of 2 levels and frequently cause false positive reactions in Salmonella tests. 5 uninoculated samples were tested using the USDA-FSIS, These can be particularly problematic in high burden foods, the DuPont Qualicon BAX (a 24 hr PCR-based method), where the initial background flora is high, allowing these BioMeriuex VIDAS (a 48 hr Fluorometric ELISA-based cross reacting bacteria to grow to levels that can cause method), and the RapidChek® SELECT™ method. problems in the rapid assay. Diagnostic approaches to Confirmation for the DuPont Qualicon BAX and alleviate these issues in the past have been solely related to BioMeriuex VIDAS methods were based on the USDA- improvement of the specificity of the assay, few if any FSIS result since they were derived from the same primary advances have targeted the selectivity/productivity of the enrichment. For the SELECT Test Kit, the samples were media. Most Salmonella media currently on the market, is confirmed by streaking to selective agar plates (XLT4 and conventional media that has been around for decades, where BGS). The results from this study are presented in Table 1. selectivity is focused on the use of antibiotics, the action of which is limited against the closely related bacteria. Results :</p><p>Strategic Diagnostics Inc., has developed a new method Table 1: Comparison of the USDA-FSIS, DuPont called RapidChek® SELECT™ for Salmonella in high Qualicon BAX, BioMeriuex VIDAS, and RapidChek® burden foods, which focuses on both the enrichment and SELECT™ Methods for the Recovery of Salmonella in detection system. Two proprietary media have been raw turkey. uniquely formulated to allow maximum selection of the target while inhibiting closely related bacteria, facilitating Competitive Method SELECT optimal productivity. The RapidChek® SELECT™ media USDA- BAX VIDAS Strip Cultural has been supplemented with a cocktail of antibiotics and FSIS Result Plate specific phage which prevent the growth of cross reactors. Method Result This is a patented media technology and a novel approach to Total 37 33 36 37 37 the enrichment of Salmonella in complex matrices. This Positives novel media combined with a newly optimized lateral flow False 0 0 0 strip, allows the best recovery and detection of Salmonella Positives spp. False 4 1 0 Negatives SDI Confidential 04-30-06 Strategic Diagnostics Inc Technical Bulletin SELECT #2</p><p>Discussion and Conclusions:</p><p>Results using the RapidChek® SELECT™ Test Kit method was comparable to all 3 competitive methods. The DuPont Qualicon BAX method produced 4 false negatives. This was not surprising since the BAX method utilizes the USDA- FSIS 18-24 hr primary enrichment broth and this may not contain a sufficiently high concentration of Salmonellae (approximately 1x103-1x104 CFU/mL) for use in the polymerase chain reaction (PCR). The RapidChek® SELECT™ Test Kit gave recovery for the C1 serovar. Another important aspect of the SELECT method is the ease of use attributes. The SELECT Test Kit requires 1 sample transfer whereas the USDA-FSIS, DuPont Qualicon BAX, and the BioMeriuex VIDAS methods require 4, 2, and 7 sample transfers, respectively. This advantage in ease-of- use, in combination with equivalent or superior performance compared to the competitive methods, is a significant advantage for the SELECT system.</p><p>For Technical & Customer Service call:</p><p>Strategic Diagnostics Inc 111 Pencader Drive Newark, DE 19702</p><p>Phone: 800-544-8881 Fax: 302-456-6782 e-mail: [email protected] www.sdix.com</p><p>Version 1.0 04- 30-06 2</p>