Comparative evaluation of the VIDAS Listeria monocytogenes Xpress (LMX) for the detection of Listeria monocytogenes in a variety of foods.

The VIDAS Listeria monocytogenes Xpress (LMX) test is an enzyme-linked fluorescent immunoassay designed for use with the automated VIDAS or mini-VIDAS instruments for the specific detection of L. monocytogenes using a 26 h proprietary enrichment broth. The VIDAS LMX method was validated according to harmonized AOAC Research Institute (RI) and Official Methods of Analysis guidelines in both the AOAC Performance Tested Method (PTM) and GovVal programs. In the PTM comparison studies, the VIDAS LMX method was compared to the U.S. Department of Agriculture-Food Safety and Inspection Service Microbiology Laboratory Guidebook, the U.S. Food and Drug Administration Bacteriological Analytical Manual, and AOAC Official Methods. The comparative food studies consisted of two main parts: internal testing and AOAC independent laboratory testing, which included seven food matrixes (deli ham, processed cheese, vanilla ice cream, cooked shrimp, smoked white fish, frozen spinach, and peanut butter). As part of the AOAC R1 GovVal program, the VIDAS LMX method was compared to the Health Canada MFHPB-30 method for the detection of L. monocytogenes in five ready-to-eat (RTE) meats (hot dogs, deli turkey, deli ham, fermented sausage, and liver paté). Twenty replicates of each inoculation level and five uninoculated controls were evaluated in each study. The LMX method also included the use ofchromogenic media, chromID Ottaviani Agosti agar and chromID L. mono. agar, for confirmation of LMX presumptive results. In both the PTM and GovVal evaluations, there were no significant differences in the Chi-square values for the LMX method when compared to reference methods. The additional parameters tested in the PTM evaluation (inclusivity, exclusivity, ruggedness, stability, and lot-to-lot) satisfied the AOAC RI performance requirements. In both the PTM and GovVal validation studies, the VIDAS LMX method demonstrated reliability as a rapid qualitative method for next-day detection of L. monocytogenes in a variety of foods, including RTE meats.

Evaluation of the GENE-UP® EHEC Detection Method for the Detection of Enterohemorrhagic E. coli in Select Foods: Collaborative Study: First Action Method 2020.06.

BACKGROUND: The GENE-UP® EHEC assay (Performance Tested MethodSM 121806) is a real-time PCR molecular detection method that utilizes fluorescence resonance energy transfer proprietary hybridization probes for the rapid detection of enterohemorrhagic Escherichia coli (EHEC) in select foods. OBJECTIVE: The purpose of this validation was to evaluate the method's interlaboratory performance and submit the results to AOAC INTERNATIONAL for adoption as a First Action Official Method of AnalysisSM for the detection of EHEC in select foods. METHOD: The GENE-UP method was evaluated in a multi-laboratory study as part of the MicroVal VALIDATION certification process using unpaired test portions for one food matrix, raw ground beef (85% lean). Collaborators evaluated the candidate method using either an automated or manual lysis procedure. The candidate method was compared to the ISO/TS 13136:2012 method. Data from 17 participants from 15 laboratories throughout the European Union were evaluated. Three levels of contamination were evaluated: a non-inoculated control level (0 CFU/test portion), a low contamination level (∼1 CFU/test portion), and a high contamination level (∼10 CFU/test portion). Data from the study were analyzed according to the probability of detection (POD) statistical model. RESULTS: The difference in laboratory probability of detection (dLPODC) values with 95% confidence interval between the candidate and reference method results were -0.01 (-0.04, 0.02), 0.23 (0.07, 0.39), and 0.06 (0.01, 0.12) for the non-inoculated, low, and high contamination levels, respectively. CONCLUSIONS: For the candidate method, values obtained for repeatability and reproducibility were similar to the reference method and indicated minimal variation between samples or between laboratories. No discrepant results (false positive or false negative) were observed for each contamination. A statistical difference was calculated between the candidate and reference method at the low and high inoculation levels, with the candidate method detecting a higher number of positive samples indicating a higher sensitivity than the reference method. No differences in the recovery of the target analyte were observed between the manual and automated lysis procedures. HIGHLIGHTS: The GENE-UP EHEC Detection Method provides end users a rapid, easy-to-use workflow for the detection of EHEC in food matrixes.

Evaluation of the GENE-UP® Listeria spp. Method for the Detection of Listeria Species in a Variety of Foods and Select Environmental Surfaces: Collaborative Study, First Action 2019.10.

BACKGROUND: The GENE-UP®  Listeria spp. 2 (LIS 2) assay (Performance Tested MethodSM 121803) is a real-time PCR molecular detection method for the rapid detection of Listeria species (Listeria monocytogenes, L. innocua, L. ivanovii, L. seeligeri, and L. welshimeri) in a variety of foods and environmental surfaces. OBJECTIVE: The purpose of this validation was to evaluate the method's interlaboratory performance and submit the results to AOAC INTERNATIONAL for adoption as First Action Official MethodSM for the detection of Listeria species in a variety of foods and select environmental surfaces. METHOD: The GENE-UP method was evaluated in a multi-laboratory study as part of the AFNOR NF VALIDATION certification process using unpaired test portions for one food matrix, full-cream goat milk cottage cheese (8.4% fat). The candidate method was compared to the ISO 11290-1/Amd.1 reference method. Sixteen participants from 15 laboratories throughout the European Union participated. Three levels of contamination were evaluated: a non-inoculated control level (0 CFU/test portion), a low contamination level (∼2 CFU/test portion), and a high contamination level (∼10 CFU/test portion). Data from that study were analyzed according to the probability of detection (POD) statistical model. RESULTS: The dLPODC values with 95% confidence intervals between the candidate and reference method results were -0.02 (-0.07, 0.03), -0.08 (-0.31, 0.16), and 0.00 (-0.03, 0.03) for the non-inoculated, low, and high contamination levels, respectively. CONCLUSIONS: The dLPODC results demonstrate no difference in performance between the candidate method and reference method for the matrix evaluated. HIGHLIGHTS: Data from a singular collaborative study was used to achieve adoption as an AOAC First Action Official Method for the detection of Listeria species in a variety of foods and select environmental surfaces.

Evaluation of the GENE-UP® Listeria monocytogenes Method for the Detection of Listeria monocytogenes in a Variety of Foods and Select Environmental Surfaces: Collaborative Study, First Action 2019.11.

BACKGROUND: The GENE-UP®  Listeria monocytogenes 2 (LMO 2) assay (Performance Tested MethodSM 121804) uses real-time PCR technology and a proprietary detection platform, the GENE-UP Thermocycler, to detect Listeria monocytogenes in a variety of foods and environmental surfaces. OBJECTIVE: The purpose of this validation was to evaluate the method's interlaboratory performance and submit the result to AOAC INTERNATIONAL for adoption as First Action Official MethodSM for the detection of Listeria monocytogenes in a variety of foods and select environmental surfaces. METHOD: The GENE-UP method was evaluated in a multi-laboratory study as part of the AFNOR NF VALIDATION certification process using unpaired test portions for one food matrix, full-cream goat milk cottage cheese (8.4% fat). The candidate method was compared to the ISO 11290-1/Amd.1:2004 reference method. Sixteen participants from 15 laboratories throughout the European Union participated. Three levels of contamination were evaluated: a non-inoculated control level (0 CFU/test portion), a low inoculum level (∼2 CFU/test portion), and a high inoculum level (∼10 CFU/test portion). Data from the study were analyzed according to the Probability of Detection (POD) statistical model as presented in the AOAC validation guidelines. RESULTS: The dLPODC values with 95% confidence interval for each comparison were; -0.02 (-0.07, 0.03), -0.08 (-0.31, 0.16), and 0.00 (-0.03, 0.03) for the non-inoculated, low, and high contamination levels, respectively. CONCLUSIONS: The dLPODC results demonstrate no difference in performance between the candidate method and reference method for the matrix evaluated. HIGHLIGHTS: The GENE-UP LMO method demonstrated accuracy and precision in detecting and discerning L. monocytogenes from other Listeria species.

Evaluation of the GENE-UP ®E. coli O157:H7 Method for the Detection of E. coli O157:H7 in Select Foods: Collaborative Study, 2019.03.

BACKGROUND: The GENE-UP®E. coli O157:H7 2 (ECO 2) assay (Performance Tested MethodSM 121805) incorporates Fluorescence Resonance Energy Transfer hybridization probes into its proprietary PCR technology for the rapid detection of E. coli O157:H7 in select foods. OBJECTIVE: The purpose of this validation was to evaluate the method's interlaboratory performance and submit the result to AOAC INTERNATIONAL for adoption as First Action Official MethodSM for the detection of E. coli O157:H7 in select foods. METHOD: The GENE-UP® method was evaluated in a multi-laboratory study as part of the MicroVal validation process using unpaired test portions for one food matrix, raw milk cheese (Comté, 34% fat, 0.8% salt). The candidate method was compared to the ISO 16654:2001 reference method. Fourteen participants from 13 laboratories throughout the European Union participated. Three levels of contamination were evaluated: a non-inoculated control level (0 colony-forming units (CFU)/test portion), a low contamination level (∼5 CFU/test portion), and a high contamination level (∼10 CFU/test portion). Data from that study were analyzed according to the Probability of Detection (POD) statistical model as presented in the AOAC validation guidelines. The difference in laboratory POD (dLPODC) values with 95% confidence interval across collaborators was calculated for each level between the candidate and reference method results, and between the candidate presumptive and confirmed results. RESULTS: The dLPODC values with 95% confidence interval were; 0.00 (-0.04, 0.04), 0.27 (0.04, 0.49), and 0.17 (0.01, 0.33) for the non-inoculated, low and high contamination levels respectively. CONCLUSIONS: The dLPODC results indicate a significant difference between the candidate method and the reference method for both the low and high contamination levels, with the candidate method producing higher recovery of the target organism at both levels. HIGHLIGHTS: The GENE-UP E. coli O157:H7 assay provides industry with a rapid, accurate detection method for E. coli O157:H7 in a broad range of foods.

Evaluation of the GENE-UP®Cronobacter Method for the Detection of Cronobacter Species in Select Foods and Environmental Surfaces: Collaborative Study, First Action 2019.01.

BACKGROUND: The GENE-UP®Cronobacter assay (Performance Tested MethodSM 081801) is a real-time PCR technology for the rapid detection of Cronobacter species in select foods and environmental surfaces. OBJECTIVE: The purpose of this validation was to evaluate the method's interlaboratory performance and submit the result to AOAC INTERNATIONAL for adoption as a First Action Official MethodSM for the detection of Cronobacter species in select foods and environmental surfaces. METHOD: The GENE-UP method was evaluated in a multilaboratory study as part of the AFNOR NF VALIDATION certification process (NF102) following ISO 16140-2:2016 using unpaired test portions for one food matrix, reconstituted infant formula containing probiotics. The candidate method was compared to the ISO 22964:2017 reference method. Sixteen participants from fifteen laboratories throughout the European Union participated. Three levels of contamination were evaluated: a noninoculated control level (0 CFU/target test portion), a low contamination level (approximately 2 CFU/target test portion), and a high contamination level (approximately 10 CFU/target test portion). Data from that study were analyzed according to the probability of detection (POD) statistical model as presented in the AOAC validation guidelines. The difference in laboratory POD (dLPODC) values with 95% confidence intervals across collaborators was calculated for each level between the candidate and reference method results and between the candidate presumptive and confirmed results. RESULTS: The dLPODC values with 95% confidence intervals were 0.00 (-0.03, 0.03), -0.08 (-0.19, 0.02), and 0.00 (-0.03, 0.03) for the noninoculated, low, and high contamination levels, respectively. CONCLUSIONS: The dLPODC results indicate no significant difference between the candidate method and the reference method or between presumptive and confirmed results for all three levels of contamination. HIGHLIGHTS: The GENE-UP Cronobacter assay provides industry with a rapid, easy to use method for the rapid detection of Cronobacter in a wide range of products and environmental samples.