3MTM Molecular Detection Assay Research Articles

Optimization of the molecular detection assay of Salmonella (MDS®) for drag swab samples of aviaries.

Detection of Salmonella sp. is important for the broiler chicken production chain because it is one microorganisms involved in food-borne diseases. Thus, this study performed the optimization of a technique of Loop-mediated isothermal DNA amplification (LAMP) through the 3MTM Molecular Detection Assay 2: Salmonella (MDS®), in accordance with Ordinance number 126 of the Ministry of Agriculture, for the detection of Salmonella sp. in drag swab. The methodology followed ISO 16140-2: 2016, with the analysis naturally contaminated drag swab samples collected from broiler aviaries and artificially contaminated with salmonella ATCCs. Of the 300 samples processed in protocol A (pre-enrichment tetrathionate broth (TT)), 45 were positive for Salmonella sp., 242 negative, one false-positive, and 12 false-negative, while of the 300 samples analyzed in protocol B (pre-enrichment brain-heart infusion broth (BHI)), 40 were positive, 256 negative, one false-positive, and three false-negative. The result for protocol A was a sensitivity of 79%, specificity of 99.6%, Positive Predictive Value (PPV) of 98%, and Negative Predictive Value (NPV) of 95%; and for protocol B, 93% sensitivity, 99.6% specificity, 98% PPV, and 99% NPV. Both protocols were associated with the reference method (p>0.05), concluding that the MDS® can be used for the qualitative detection of Salmonella sp.

Validation of the 3M™ Molecular Detection Assay 2-STEC Gene Screen (stx and eae) for Detection of Shiga Toxin Gene (stx1 and/or stx2) and Intimin Gene (eae) in Dried Cannabis Flower and Dried Hemp Flower: AOAC Performance Tested MethodSM 071902.

The 3M™ Molecular Detection Assay 2-STEC Gene Screen (stx and eae) method is based on gene amplification by the use of real time loop-mediated isothermal amplification when used with the 3M Molecular Detection System for the rapid and specific detection of Shiga toxin gene (stx1 and/or stx2) and intimin gene (eae) from Shiga toxin-producing Escherichia coli (STEC) in enriched products. The 3M Molecular Detection Assay 2-STEC Gene Screen (stx and eae) was approved as AOAC Performance Tested MethodSM Certificate No. 071902. This matrix extension study evaluated the 3M Molecular Detection Assay 2-STEC Gene Screen (stx and eae) method for detection of STECs in dried cannabis flower [>0.3% delta 9-tetrahydrocannabinol (THC)] and dried hemp flower (≤0.3% THC) at a 10 g test portion size. Testing followed procedures outlined in 3M Molecular Detection Assay 2-STEC Gene Screen (stx and eae) product instructions and Standard Method Performance Requirements (SMPR®) for Detection of Shiga Toxin-Producing Escherichia coli in Cannabis and Cannabis Products (AOAC SMPR 2020.012). The method was evaluated at low, high, and non-inoculated levels. Results showed no statistically significant difference between the presumptive positive 3M Molecular Detection Assay 2-STEC Gene Screen (stx and eae) results and the SMPR 2020.012 recommended cultural confirmations. This study provides data that demonstrate the 3M Molecular Detection Assay 2-STEC Gene Screen (stx and eae) is a reliable method for the rapid and specific detection of STEC organisms in dried cannabis flower and dried hemp flower. The 3M Molecular Detection Assay 2-STEC Gene Screen (stx and eae) method is suitable for the rapid and specific detection of STEC organisms in dried cannabis flower and dried hemp flower.

Validation of the 3M™ Molecular Detection Assay 2-STEC Gene Screen (stx) for Detection of Shiga Toxin Gene (stx1 and/or stx2) in Dried Cannabis Flower and Dried Hemp Flower: AOAC Performance Tested MethodSM 071903.

The 3M™ Molecular Detection Assay 2-STEC Gene Screen (stx) method is based on gene amplification by the use of real-time loop-mediated isothermal amplification when used with the 3M Molecular Detection System for the rapid and specific detection of Shiga toxin gene (stx1 and/or stx2) from Shiga toxin-producing Escherichia coli (STEC) in enriched products. The 3M Molecular Detection Assay 2-STEC Gene Screen (stx) was approved as AOAC Performance Tested MethodSM Certificate No. 071903. This matrix extension study evaluated the 3M Molecular Detection Assay 2-STEC Gene Screen (stx) method for detection of STECs in dried cannabis flower [>0.3% delta 9-tetrahydrocannabinol (THC)] and dried hemp flower (≤0.3% THC) at a 10 g test portion size. Testing followed procedures outlined in 3M Molecular Detection Assay 2-STEC Gene Screen (stx) product instructions and Standard Method Performance Requirement (SMPR®) for Detection of Shiga Toxin-Producing Escherichia coli in Cannabis and Cannabis Products (AOAC SMPR 2020.012). The method was evaluated at low, high, and non-inoculated levels. Results showed no statistically significant difference between the presumptive positive 3M Molecular Detection Assay 2-STEC Gene Screen (stx) results and the SMPR 2020.012 recommended cultural confirmations. This study provides data that demonstrate the 3M Molecular Detection Assay 2-STEC Gene Screen (stx) is a reliable method for the rapid and specific detection of STECs in dried cannabis flower and dried hemp flower. The 3M Molecular Detection Assay 2-STEC Gene Screen (stx) method is suitable for the rapid and specific detection of STECs in dried cannabis flower and dried hemp flower.

Validation of the 3MTM Molecular Detection Assay 2-Salmonella for detection of Salmonella in Dried Cannabis Flower and Dried Hemp Flower: AOAC Performance Tested MethodsSM 091501.

The 3M™ Molecular Detection Assay 2-Salmonella method is based on real-time loop-mediated isothermal amplification when used with the 3M Molecular Detection System for the rapid and specific detection of Salmonella in enriched products. The 3M Molecular Detection Assay 2-Salmonella was approved as AOAC INTERNATIONAL (AOAC) Performance Tested MethodSM (PTM) Certificate No. 091501 and as AOAC Official Method of AnalysisSM2016.01. This matrix extension study evaluated the 3M Molecular Detection Assay 2-Salmonella for detection of Salmonella in dried cannabis flower [>0.3% delta 9-tetrahydrocannabinol (THC)] and dried hemp flower (≤0.3% THC) at a 10 g test portion size. Matrix studies in dried cannabis and hemp flowers followed procedures outlined in 3M Molecular Detection Assay 2-Salmonella product instructions and Standard Method Performance Requirement (SMPR®) for Detection of Salmonella species in Cannabis and Cannabis Products (AOAC SMPR 2020.002). The method was evaluated at low, high, and non-contaminated levels. Results showed no statistically significant difference between the presumptive positive 3M Molecular Detection Assay 2-Salmonella results and the SMPR 2020.002 recommended cultural confirmations. This study demonstrates that the 3M Molecular Detection Assay 2-Salmonella is a reliable method for the rapid and specific detection of Salmonella in dried cannabis flower and dried hemp flower. The 3M Molecular Detection Assay 2-Salmonella method is suitable for the rapid and specific detection of Salmonella in dried cannabis flower and dried hemp flower.

Validation of the 3M™ Molecular Detection Assay 2 - STEC Gene Screen (stx) for the Detection of Shiga Toxin Gene (stx1 and/or stx2) in Additional Matrixes: AOAC Performance Tested MethodSM 071903.

BackgroundThe 3M™ Molecular Detection Assay 2 - STEC Gene Screen (stx) method is based on gene amplification by the use of real-time loop-mediated isothermal amplification when used with the 3M Molecular Detection System for the rapid and specific detection of Shiga toxin gene (stx1 and/or stx2) from Shiga toxin-producing enterohemorrhagic Escherichia coli (STEC) in enriched foods.ObjectiveThe 3M Molecular Detection Assay 2 - STEC Gene Screen (stx) method was evaluated as a Level 2 method modification to add new matrixes to the certified claim: 25 g fresh raw ground beef (approximately 75% lean), 375 g raw beef trim (approximately 75% lean), 375 g fresh raw ground pork (approximately 70% lean), 375 g fresh raw poultry parts, and 25 g sprouts.MethodsMatrix studies were conducted to assess the method’s performance compared to the US Department of Agriculture Food Safety and Inspection Service Microbiology Laboratory Guidebook, 5C.00 for meat and poultry, and to the US Food and Drug Administration Bacteriological Analytical Manual, Ch. 4A for sprouts, using an unpaired study design.ResultsThe 3M Molecular Detection Assay 2 - STEC Gene Screen (stx) method demonstrated no significant differences between presumptive and confirmed results or between candidate and reference method results for any of the matrices tested.Conclusion and HighlightsThe data collected in these studies demonstrate that the 3M Molecular Detection Assay 2 - STEC Gene Screen (stx) is a reliable method for the rapid and specific detection of STEC in fresh raw ground beef (approximately 75% lean), fresh raw beef trim (approximately 75% lean), fresh raw ground pork (approximately 70% lean), fresh raw poultry parts, and sprouts.

Validation of the 3M™ Molecular Detection Assay 2 - STEC Gene Screen (stx and eae) for the Detection of Shiga Toxin Gene (stx1 and/or stx2) and Intimin Gene (eae): AOAC Performance Tested MethodSM 071902.

BackgroundThe 3M™ Molecular Detection Assay 2 - STEC Gene Screen (stx and eae) method is based on gene amplification by the use of real-time loop-mediated isothermal amplification when used with the 3M Molecular Detection System for the rapid and specific detection of Shiga toxin gene (stx1 and/or stx2) and intimin gene (eae) from Shiga toxin-producing enterohemorrhagic Escherichia coli (STEC) in enriched foods.ObjectiveThe 3M Molecular Detection Assay 2 - STEC Gene Screen (stx and eae) method was evaluated as a Level 2 method modification to add new matrixes to the certified claim: 25 g fresh raw ground beef (approximately 75% lean), 375 g fresh raw ground pork (approximately 70% lean), 375 g fresh raw poultry parts, and 25 g sprouts.MethodsMatrix studies were conducted to assess the method’s performance compared to the U. S. Department of Agriculture Food Safety and Inspection Service Microbiology Laboratory Guidebook, 5C.00 for meat and poultry, and to the U. S. Food and Drug Administration Bacteriological Analytical Manual, Ch. 4A for sprouts, using an unpaired study design.ResultsThe 3M Molecular Detection Assay 2 - STEC Gene Screen (stx and eae) method demonstrated no significant differences between presumptive and confirmed results or between candidate and reference method results for any of the matrixes tested.Conclusion and HighlightsThe data collected in these studies demonstrate that the 3M Molecular Detection Assay 2 - STEC Gene Screen (stx and eae) is a reliable method for the rapid and specific detection of STEC in fresh raw ground beef (approximately 75% lean), fresh raw ground pork (approximately 70% lean), fresh raw poultry parts, and sprouts.

Validation of the 3M™ Molecular Detection Assay 2 - STEC Gene Screen (stx) for the Detection of Shiga Toxin Gene (stx1 and/or stx2) in Fresh Raw Ground Beef and Fresh Spinach: AOAC Performance Tested MethodSM 071903.

BackgroundThe 3M™ Molecular Detection Assay 2 - STEC Gene Screen (stx) method is based on gene amplification by the use of real time loop-mediated isothermal amplification when used with the 3M Molecular Detection System for the rapid and specific detection of Shiga toxin gene (stx1 and/or stx2) from Shiga toxin-producing Escherichia coli (STEC) in enriched foods. The stx assay does not differentiate between stx1 and stx2 but detects the presence of stx1 and/or stx2.ObjectiveThe 3M Molecular Detection Assay 2 - STEC Gene Screen (stx) method was evaluated for AOAC® Performance Tested MethodsSM certification.MethodsMatrix studies, inclusivity/exclusivity, robustness testing, product stability, and lot-to-lot variability testing were conducted to assess the method’s performance.ResultsThe 3M Molecular Detection Assay 2 - STEC Gene Screen (stx) demonstrated equivalent results to the United States Department of Agriculture/Food Safety and Inspection Service Microbiology Laboratory Guidebook Chapter 5C.00 reference method for fresh raw ground beef, and the U.S. Food and Drug Administration Bacteriological Analytical Manual Chapter 4A reference method for fresh spinach. The 3M Molecular Detection Assay 2 - STEC Gene Screen (stx) detected all STEC E. coli strains (E. coli strains with stx1 and/or stx2 genes) and did not detect any of the 45 strains from the exclusivity panel. Robustness testing indicated that small variations in critical test parameters did not adversely affect the assay’s performance. Product consistency and stability testing demonstrated no differences between the lots evaluated.ConclusionThe data collected in these studies demonstrate that the 3M Molecular Detection Assay 2 - STEC Gene Screen (stx) is a reliable method for the rapid and specific detection of Shiga toxin-producing E. coli in raw ground beef and spinach.HighlightsThe 3M Molecular Detection Assay 2 - STEC Gene Screen (stx) method is suitable for the rapid and specific detection of Shiga toxin-producing E. coli in fresh raw ground beef, and spinach.

Validation of the 3M™ Molecular Detection Assay 2 - STEC Gene Screen (stx and eae) for the Detection of Shiga Toxin Gene (stx and eae) in Fresh Raw Beef Trim, Fresh Raw Ground Beef and Fresh Spinach: AOAC Performance Tested MethodSM 071902.

BackgroundThe 3M™ Molecular Detection Assay 2 - STEC Gene Screen (stx and eae) method is based on gene amplification using real time loop-mediated isothermal amplification with the 3M Molecular Detection System for the rapid and specific detection of Shiga toxin gene (stx1 and/or stx2) and intimin gene (eae) from Shiga toxin-producing enterohemorrhagic Escherichia coli (STEC) in enriched foods.ObjectiveThe 3M Molecular Detection Assay 2 - STEC Gene Screen (stx and eae) method was evaluated for AOAC® Performance Tested MethodsSM certification.MethodsMatrix studies, inclusivity/exclusivity, robustness, product stability, and lot-to-lot variability testing were conducted to assess the method’s performance.ResultsThe 3M Molecular Detection Assay 2 - STEC Gene Screen (stx and eae) demonstrated equivalent results to the US Department of Agriculture–Food Safety and Inspection Service Microbiology Laboratory Guidebook 5C.00 for fresh raw beef trim and fresh raw ground beef, and to the US Food and Drug Administration Bacteriological Analytical Manual Chapter 4A for fresh spinach. The 3M Molecular Detection Assay 2 - STEC Gene Screen (stx and eae) detected 50 of 50 E. coli strains with stx1 and/or stx2 genes, and the eae gene, and detected zero of 40 strains from the exclusivity panel. Robustness testing indicated that small variations in critical test parameters did not adversely affect the assay’s performance. Product consistency and stability testing demonstrated no differences between the lots evaluated.ConclusionThe data collected demonstrates that the 3M Molecular Detection Assay 2 - STEC Gene Screen (stx and eae) is a reliable method for the rapid and specific detection of STEC in raw beef trim, raw ground beef, and spinach.HighlightsThe 3M Molecular Detection Assay 2 - STEC Gene Screen (stx and eae) method is suitable for the rapid and specific detection of STECs in raw beef trim, raw ground beef, and spinach.

Evaluation of Simple and Rapid Shiga Toxin Gene Detection of Enterohemorrhagic Escherichia coliin Food Using 3MTM Molecular Detection Assay2-STEC Gene Screen Kit

The sensitivity of the 3M TM Molecular Detection Assay 2-STEC Gene Screen (stx) assay (3M MDA2 STEC assay) was evaluated for verotoxin (VT) gene screening from food materials. The pure culture and foods such as sliced beef, tandoori paste, cucumber, etc. were used for this study. The sensitivity was obtained as 3 to 4 log CFU/mL in enrichment broth (BPW and mEC), which was cultured with food matrices. These results showed this detection kit was suitable the notification of standard methods from Ministry of health, which requires 4 log CFU/mL as detection limit in enrichment broth. This assay was useful as a rapid and simple screening method for VT gene from foods.

Evaluation of a commercial loop-mediated isothermal amplification assay, 3MTM Molecular Detection Assay 2 – Campylobacter, for the detection of Campylobacter from poultry matrices

ABSTRACT 1. The objective of this study was to evaluate performance of a commercial loop-mediated isothermal amplification (LAMP) method as an alternative method for the detection of Campylobacter spp. in primary production samples, poultry rinses and raw poultry products, as compared to the US Department of Agriculture Food Inspection Service Microbiology Laboratory Guide Book PCR reference method, MLG 41A. 2. The Campylobacter spp. LAMP was used in conjunction with a ready-to-use enrichment broth that does not require microaerophilic incubation. After enrichment, boot swabs from poultry farms, carcase rinses and raw poultry products were tested by the LAMP method and the MLG 41A PCR method. 3. The ready-to-use enrichment broth enabled the growth of Campylobacter spp. within 22 to 28 hours under aerobic incubation conditions. The LAMP method enabled Campylobacter detection in the enriched samples of various poultry matrices and had equivalent sensitivity and specificity to the MLG 41A PCR method. 4. No significant difference (95% confidence interval) was found between the alternative and the MLG 41A PCR method, as determined by probability of detection analysis, except for neutralising buffered peptone water post-chill rinsates. For the post-chill neutralising buffered peptone water rinsates, the LAMP method had significantly higher confirmed portions.

Evaluation of 3M™ loop-mediated isothermal amplification-based kit and 3M™ ready-to-use plating system for detection of Listeria in naturally contaminated leafy vegetables, chicken, and their related processing environments.

The effectiveness of two different rapid methods involving the 3M™ molecular detection assay Listeria and the 3M™ Petrifilm environmental Listeria Plate were evaluated for the rapid detection of Listeria from naturally contaminated vegetables and chicken-processing environments against the standard culture-based method. A total of 178 samples were examined for the presence of Listeria. A total of 47/178 (26.4%) by standard ISO culture-based method (EN ISO 11290-1), 42/178 (23.6%) by 3M™ MDA Listeria and 40/178 (22.5%) by 3M™ Petrifilm EL Plate showed positive results, respectively. The accuracy, sensitivity, specificity, positive predictive value, and negative predictive value for 3M™ MDA Listeria and 3M™ Petrifilm EL Plate were 97.2, 89.4, 99.3, 97.7, 96.4% and 96.1, 85.1, 100.0, 100.0, 94.9%, respectively. Based on the Cohen's Kappa value, there was a complete and robust concordance between 3M™ MDA Listeria (0.911) and 3M™ Petrifilm EL Plates (0.894) as compared to the standard culture-based method.

Loop-mediated isothermal amplification (LAMP) for rapid detection of L. monocytogenes in meat

There is a continued need to develop improved rapid methods for detection of foodborne pathogens. Rapid and sensitive methods for enumeration of Listeria monocytogenes are important for microbiological food safety testing purpose. The aim of this project was to evaluate a commercial loop-mediated isothermal amplification (LAMP) based system with bioluminescence, named as 3M™ Molecular Detection Assay (MDA), was validated for the detection of L. monocytogenes in food products with a standard GOST 32031-2012 method as reference. The results of this study revealed that a commercial LAMP-based method performed equally effective compared with method, showing from 94% to 100% specificity and sensitivity, respectively. The LAMP-based method was shown to be rapid and reliable detection technique for L. monocytogenes present at low numbers (10 CFU.g-1) on raw meat and meat products and can be applicable in meat industry. Thus, compared with the microbiological method based GOST 32031-2012, the LAMP assay is a relatively rapid and highly sensitive method for detecting L. monocytogenes and will facilitate the surveillance for contamination of L. monocytogenes in food. The 3M MDS result and culture-based detection (GOST 32031-2012) did not differ significantly (p >0.05) regarding the number of positive samples.

Evaluation of the 3M™ Molecular Detection Assay (MDA) 2 - Cronobacter for the Detection of Cronobacter species in Select Foods and Environmental Surfaces: Collaborative Study, First Action 2018.01.

The 3M™ Molecular Detection Assay (MDA) 2 - Cronobacter combines the use of loop-mediated isothermal amplification to rapidly amplify nucleic acid sequences while using bioluminescence to detect the amplification. Using a paired study design, the MDA 2 - Cronobacter was compared with ISO 22964:2017 for the detection of Cronobacter species in powdered infant formula containing probiotics. Technicians from 11 laboratories from the United States, Mexico, and Croatia participated. Collaborators received test portions with three levels of contamination. Statistical analysis was conducted according to the probability of detection (POD) statistical model. Results obtained for the low-inoculum level test portions produced a difference in POD values obtained from combining all valid collaborator POD data values with 95% confidence intervals of -0.01, -0.12, and 0.10, indicating that the difference between methods was not statistically significant at the 0.05 probability level.

Evaluation of Roka Atlas Salmonella method for the detection of Salmonella in egg products in comparison with culture method, real-time PCR and isothermal amplification assays

With the increasing focus on the food safety, rapid methods for the detection of Salmonella are crucial for both food industry and regulatory agencies. Recently, many molecular methodologies with diverse technologies have been introduced. Roka Atlas®Salmonella Assay (SEN) is a molecular method that uses ribosomal RNA as target for detection, which is theoretically more sensitive than PCR or isothermal amplification methods that target the DNA sequences of single genes. In this study, SEN assay was compared with four PCR- and isothermal amplification-based assays and a culture method, such as the MicroSEQ®Salmonella spp. Detection kit (MicroSEQ), 3M™ Molecular Detection Assay (MDA) Salmonella, ANSRTMSalmonella Assay (ANSR), and Pro-AmpRTTM SALM spp. Kit (Pro-AmpRT). Food samples were prepared and analyzed according to the current U. S. Food and Drug Administration (FDA) Bacteriological Analytical Manual (BAM) Salmonella culture method. A total of 155 bacterial isolates (121 for Salmonella inclusivity and 34 for Salmeonlla exclusivity) and 200 egg product samples inoculated at a level of 1–5 CFU/25 g were analyzed. The study also estimated the limit of detection of these molecular methods, and illustrated their advantages and disadvantages. For exclusivity, all 34 non-Salmonella isolates were negative by all 5 molecular methods studied. For inclusivity, all 121 Salmonella isolates were positive by MDA, ANSR, and Pro-AmpRT methods. However, the SEN and MicroSEQ results were negative for 9 samples inoculated with Salmonella bongori. The detection limit of the 5 molecular methods ranged from 1.76 to 3.76 log CFU/mL pre-enrichment culture, with the SEN assay being the most sensitive (1.76 – 2.64 log CFU/mL). The results indicated that the SEN assay was as effective and sensitive in detecting Salmonella enterica in egg products as was the FDA BAM culture method and the 4 other isothermal amplification and PCR methods evaluated in the study.

Evaluation of the 3M™ Molecular Detection Assay (MDA) 2 - Listeria monocytogenes for the Detection of Listeria monocytogenes in a Variety of Foods and Select Environmental Surfaces: Collaborative Study, First Action 2016.08.

The 3M™ Molecular Detection Assay (MDA) 2 - Listeria monocytogenes uses loop-mediated isothermal amplification of unique DNA target sequences combined with bioluminescence to rapidly detect Listeria monocytogenes in a broad range of food types and on environmental surfaces. Using an unpaired study design, technicians from 13 laboratories located in the United States and Canada compared the 3M MDA 2 - Listeria monocytogenes to the U.S. Department of Agriculture Food Safety Inspection Service Microbiology Laboratory Guidebook Chapter 8.09 "Isolation and Identification of Listeria monocytogenes from Red Meat, Poultry, and Egg Products, and Environmental Samples" reference method for the detection of L. monocytogenes in deli turkey and raw chicken breast fillet. Each matrix was evaluated at three levels of contamination: 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). Statistical analysis was conducted according to the probability of detection (POD) statistical model. Results obtained for the low inoculum level test portions produced a difference in the collaborating laboratory POD (dLPOD) value of 0.04 with a 95% confidence interval of (-0.08, 0.17) for deli turkey, indicating that the difference between methods was not statistically significant at the 0.05 probability level. For raw chicken breast fillet, a dLPOD value of 0.16 with a 95% confidence interval of (0.04, 0.28) indicated a statistically significant difference, with an observed higher proportion of positive results by the candidate method compared to the reference method.

Evaluation of the 3M™ Molecular Detection Assay (MDA) 2 - Salmonella for the Detection of Salmonella spp. in Select Foods and Environmental Surfaces: Collaborative Study, First Action 2016.01.

The 3M™ Molecular Detection Assay (MDA) 2 - Salmonella uses real-time isothermal technology for the rapid and accurate detection of Salmonella spp. from enriched select food, feed, and food-process environmental samples. The 3M MDA 2 - Salmonella was evaluated in a multilaboratory collaborative study using an unpaired study design. The 3M MDA 2 - Salmonella was compared to the U.S. Food and Drug Administration Bacteriological Analytical Manual Chapter 5 reference method for the detection of Salmonella in creamy peanut butter, and to the U.S. Department of Agriculture, Food Safety and Inspection Service Microbiology Laboratory Guidebook Chapter 4.08 reference method "Isolation and Identification of Salmonella from Meat, Poultry, Pasteurized Egg and Catfish Products and Carcass and Environmental Samples" for the detection of Salmonella in raw ground beef (73% lean). Technicians from 16 laboratories located within the continental United States participated. Each matrix was evaluated at three levels of contamination: 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). Statistical analysis was conducted according to the probability of detection (POD) statistical model. Results obtained for the low inoculum level test portions produced difference in collaborator POD values of 0.03 (95% confidence interval, -0.10 to 0.16) for raw ground beef and 0.06 (95% confidence interval, -0.06 to 0.18) for creamy peanut butter, indicating no statistically significant difference between the candidate and reference methods.

Evaluation of commercial loop-mediated isothermal amplification based kit and ready-to-use plating system for detection of Salmonella in naturally contaminated poultry and their processing environment

This current research evaluated the efficacy of two rapid methods: the 3M™ Molecular Detection Assay (MDA) and the 3M™ Petrifilm™ Salmonella Express (SALX) System against culture-based method for the detection of Salmonella in naturally contaminated poultry and their environment. One hundred forty five samples consisting of whole chickens, chicken cuts and environmental samples were analysed for the presence of Salmonella. 133 (91.7%), 124 (85.5%) and 123 (84.8%) samples were positive by the culture-based method, 3M MDA and 3M Petrifilm SALX System, respectively. The sensitivity, specificity, negative predictive value, positive predictive value and accuracy for the 3M MDA were 93.2, 91.7, 55.0, 99.2 and 93.1%, respectively. Similarly, the sensitivity, specificity, negative predictive value, positive predictive value and accuracy for the 3M Petrifilm SALX System were 92.5, 100.0, 54.5, 100.0 and 93.1%, respectively. Both 3M MDA and 3M Petrifilm SALX System yielded similar kappa results, indicating substantial agreement with the culture-based method. The data from this study therefore supports the use of the 3M Petrifilm SALX System and the 3M MDA as rapid and reliable screening methods for Salmonella detection in poultry and its processing environment.

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

A commercial loop-mediated isothermal amplification (LAMP) based system with bioluminescence, named as 3M™ Molecular Detection Assay (MDA), was validated for the detection of Listeria monocytogenes (3-strain cocktail) at low levels (100, 101, 102 CFU/100 cm2) inoculated on stainless steel (SS) and polyethylene (PE) surfaces, with and without (w/o) organic load (OL) of cold-smoked salmon homogenate by comparing with a standard ISO method as reference. The results of this study revealed that a commercial LAMP-based method performed equally effective compared with ISO method at inoculum levels of 100 and 102/100 cm2, showing 100% specificity and sensitivity, respectively. At 101 CFU/100 cm2, a slight reduction in the effectiveness of LAMP-based method was observed most likely due to the use of single enrichment step in the procedure of LAMP-based method. The LAMP-based method was shown to be rapid and reliable detection technique for L. monocytogenes present at low numbers on food processing surfaces, regardless of organic residues, and can be applicable in seafood industry.

Evaluation of 3M™ Molecular Detection Assay (MDA) Listeria monocytogenes for the Detection of Listeria monocytogenes in Selected Foods and Environmental Surfaces: Collaborative Study, First Action 2014.07.

The 3M™ Molecular Detection Assay (MDA) Listeria monocytogenes combines isothermal amplification and bioluminescence to detect Listeria monocytogenes with high specificity and efficiency in select foods and environmental samples. The 3M MDA Listeria monocytogenes method was evaluated 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 8.09 (2011) Isolation and Identification of Listeria monocytogenes from Red Meat, Poultry, and Egg Products and Environmental Samples for deli turkey, and the AOAC Official Method of Analysis(SM) 993.12 Listeria monocytogenes in Milk and Dairy Products for full-fat (4% milk fat) cottage cheese following the current AOAC guidelines. A total of 16 laboratories located in the continental United States and Canada participated in this collaborative study. For deli turkey, 125 g test portions were evaluated using heat-stressed cells by each method. For full-fat cottage cheese, 25 g test portions were evaluated using nonheat-stressed cells. Each matrix had three inoculation levels: an uninoculated control level (0 CFU/test portion), and two levels artificially contaminated with L. monocytogenes, a low inoculum level (0.2-2 CFU/test portion) and a high inoculum level (2-5 CFU/test portion). In total, 1584 unpaired replicate samples were analyzed. Statistical analysis was conducted according to the probability of detection (POD) model. Results obtained for the low inoculum level full-fat cottage cheese test portions produced a difference in cross-laboratory POD (dLPOD) value of -0.08 with a 95% confidence interval (CI) of (-0.20, 0.05). For the low-level deli turkey test portions, a dLPOD value of -0.02 with a 95% CI of (-0.14, 0.11) was obtained.

Evaluation of 3M™ Molecular Detection Assay (MDA) Listeria for the Detection of Listeria species in Selected Foods and Environmental Surfaces: Collaborative Study, First Action 2014.06.

The 3M™ Molecular Detection Assay (MDA) Listeria is used with the 3M Molecular Detection System for the detection of Listeria species in food, food-related, and environmental samples after enrichment. The assay utilizes loop-mediated isothermal amplification to rapidly amplify Listeria target DNA with high specificity and sensitivity, combined with bioluminescence to detect the amplification. The 3M MDA Listeria method was evaluated using an unpaired study design in a multilaboratory collaborative study and compared to the AOAC Official Method of AnalysisSM (OMA) 993.12 Listeria monocytogenes in Milk and Dairy Products reference method for the detection of Listeria species in full-fat (4% milk fat) cottage cheese (25 g test portions). A total of 15 laboratories located in the continental United States and Canada participated. Each matrix had three inoculation levels: an uninoculated control level (0 CFU/test portion), and two levels artificially contaminated with Listeria monocytogenes, a low inoculum level (0.2-2 CFU/test portion) and a high inoculum level (2-5 CFU/test portion) using nonheat-stressed cells. In total, 792 unpaired replicate portions were analyzed. Statistical analysis was conducted according to the probability of detection (POD) model. Results obtained for the low inoculum level test portions produced a difference in cross-laboratory POD value of -0.07 with a 95% confidence interval of (-0.19, 0.06). No statistically significant differences were observed in the number of positive samples detected by the 3M MDA Listeria method versus the AOAC OMA method.