Evaluation of 3M™ Molecular Detection Assay (MDA) Salmonella for the Detection of Salmonella in Selected Foods: Collaborative Study

Abstract

The 3M Molecular Detection Assay (MDA) Salmonella is used with the 3M Molecular Detection System for the detection of Salmonella spp. in food, food-related, and environmental samples after enrichment. The assay utilizes loop-mediated isothermal amplification to rapidly amplify Salmonella target DNA with high specificity and sensitivity, combined with bioluminescence to detect the amplification. The 3M MDA Salmonella method was compared using an unpaired study design in a multilaboratory collaborative study to the U.S. Department of Agriculture/Food Safety and Inspection Service-Microbiology Laboratory Guidebook (USDA/FSIS-MLG 4.05), Isolation and Identification of Salmonella from Meat, Poultry, Pasteurized Egg and Catfish Products for raw ground beef and the U.S. Food and Drug Administration/Bacteriological Analytical Manual (FDA/BAM) Chapter 5 Salmonella reference method for wet dog food following the current AOAC guidelines. A total of 20 laboratories participated. For the 3M MDA Salmonella method, raw ground beef was analyzed using 25 g test portions, and wet dog food was analyzed using 375 g test portions. For the reference methods, 25 g test portions of each matrix were analyzed. Each matrix was artificially contaminated with Salmonella at three inoculation levels: an uninoculated control level (0 CFU/test portion), a low inoculum level (0.2-2 CFU/test portion), and a high inoculum level (2-5 CFU/test portion). In this study, 1512 unpaired replicate samples were analyzed. Statistical analysis was conducted according to the probability of detection (POD). For the low-level raw ground beef test portions, the following dLPOD (difference between the POD of the reference and candidate method) values with 95% confidence intervals were obtained: -0.01 (-0.14, +0.12). For the low-level wet dog food test portions, the following dLPOD with 95% confidence intervals were obtained: -0.04 (-0.16, +0.09). No significant differences were observed in the number of positive samples detected by the 3M MDA Salmonella method versus either the USDA/FSIS-MLG or FDA/BAM methods.

Loop-mediated isothermal amplification (LAMP) coupled with bioluminescence for the detection of Listeria monocytogenes at low levels on food contact surfaces

“…False positive (F pos ) results were obtained in this study, and have also been reported previously for LAMP-based technique (Bird et al, 2013;Vongkamjan et al, 2015). Usually, in order to amplify six to eight target DNA regions, the LAMP employs from four to six primers with much higher concentration than that used in traditional PCR-based methods, which may lead to an increased probability of non-specific amplification induced by formed primer dimers, giving the false positive results (Wang, Brewster, Paul, & Tomasula, 2015).…”

“…Similarly, Martinon et al (2012) reported that the real-time molecular methods (PCR, PMA-PCR) overestimated L. monocytogenes counts on environmental surfaces compared to the culture technique. However, the occurrence of false-positive results may be significantly reduced by avoiding cross-contamination, high humidity and temperatures, when handling reaction tubes and inadequate reaction volumes (Bird et al, 2013;Wang et al, 2015). Nevertheless, apart from a few disadvantages of LAMP technique, it was equally effective as reference ISO method for L. monocytogenes detection, but it reduced significantly the total time of analysis (from minimum 5 days for ISO to less than 2 days including the enrichment time).…”

Detection of Salmonella in Foods Using a Reference PN-ISO Method and an Alternative Method Based on Loop-mediated Isothermal Amplification Coupled with Bioluminescence

“…The alternative method used 3M Molecular Detection Assay for salmonella tests, which are used with the Molecular Detection System (MDS) for the quick detection of these bacteria in food samples [23]. Premultiplication was carried out in standard peptone buffered water at 37°C within 18-24 h. The procedure related to the use of 3M MDS tests involved the transfer of the multiplied culture to tubes with a lysing solution and lysis for 15 min at 100°C in the first stage, and then a quick cooling within 10 min at room temperature.…”

Evaluation of Commercial Kit Based on Loop-Mediated Isothermal Amplification for Rapid Detection of Low Levels of Uninjured and Injured Salmonella on Duck Meat, Bean Sprouts, and Fishballs in Singapore

“…The detection of Salmonella cells by the commercial LAMP-based kit (3M Molecular Detection Assay Salmonella; 3M) was performed according to the manufac turer's manual (2). Briefly, 20 pi of BPW enrichment was added to a tube with lysis solution.…”

“…Similar to most nucleic acid-based sequence amplification detection methods, this commercial LAMPbased kit does not require costly instrumentation, such as thermal cyclers. LAMP is also characterized by higher specificity and sensitivity, and it significantly shortens the time of DNA amplification due to isothermal reaction conditions (2,5,9).…”