Probability of Detection Analysis in Multi-Hit Flaw Detection

Author(s):  
Ajay M. Koshti
2019 ◽  
Vol 102 (3) ◽  
pp. 926-935
Author(s):  
Quynh-Nhi Le ◽  
Susan Alles ◽  
Brooke Roman ◽  
Eric Tovar ◽  
Edan Hosking ◽  
...  

Abstract Background: Listeria Right NowTM is a novel, enrichment-free molecular method for detection of Listeria spp. in swab samples from environmental surfaces. The test provides results in real time, indicating the current or recent presence of Listeria spp. in the environment. After sampling, the entire contents of the swab are subject to sample processing, releasing large quantities of target ribosomal RNA molecules into the lysate. A portion of the lysate is then tested using the ANSR® for Listeria isothermal nucleic acid amplification assay. Objective: A Performance Tested MethodSM study was conducted to validate the method for detection of Listeria spp. in swab samples from stainless steel and sealed concrete surfaces. Methods and Results: In inclusivity testing, 60 of 60 Listeria spp. strains tested positive. In exclusivity testing, 31 of 31 nontarget bacterial strains tested negative. In LOD testing, the test was able to detect as few as 2 CFU of L. monocytogenes applied to a stainless steel surface. In matrix testing of inoculated stainless steel and sealed concrete surfaces, there were no statistically significant differences in method performance comparing the Listeria Right Now and U.S. Food and Drug Administration Bacteriological Analytical Manual reference culture procedures as determined by probability of detection analysis. In robustness testing, modest changes to three assay operating parameters simultaneously did not significantly affect performance of the test. Conclusions and Highlights: Results can be obtained in less than 1 h using the Listeria Right Now test, allowing food industry personnel to take immediate corrective action in the case of Listeria contamination incidents.


2018 ◽  
Vol 101 (5) ◽  
pp. 1490-1507
Author(s):  
Gregory Juck ◽  
Verapaz Gonzalez ◽  
Ann-Christine Olsson Allen ◽  
Meredith Sutzko ◽  
Kody Seward ◽  
...  

Abstract The Romer Labs RapidChek®Listeria monocytogenes test system (Performance Tested Method 011805) was validated against the U.S. Department of Agriculture-Food Safety and Inspection Service Microbiology Laboratory Guidebook (USDA-FSIS/MLG), U.S. Food and Drug Association Bacteriological Analytical Manual (FDA/BAM), and AOAC Official Methods of Analysis (AOAC/OMA) cultural reference methods for the detection of L. monocytogenes on selected foods including hot dogs, frozen cooked breaded chicken, frozen cooked shrimp, cured ham, and ice cream, and environmental surfaces including stainless steel and plastic in an unpaired study design. The RapidChek method uses a proprietary enrichment media system, a 44–48 h enrichment at 30 ± 1°C, and detects L. monocytogenes on an immunochromatographic lateral flow device within 10 min. Different L. monocytogenes strains were used to spike each of the matrixes. Samples were confirmed based on the reference method confirmations and an alternate confirmation method. A total of 140 low-level spiked samples were tested by the RapidChek method after enrichment for 44–48 h in parallel with the cultural reference method. There were 88 RapidChek presumptive positives. One of the presumptive positives was not confirmed culturally. Additionally, one of the culturally confirmed samples did not exhibit a presumptive positive. No difference between the alternate confirmation method and reference confirmation method was observed. The respective cultural reference methods (USDA-FSIS/MLG, FDA/BAM, and AOAC/OMA) produced a total of 63 confirmed positive results. Nonspiked samples from all foods were reported as negative for L. monocytogenes by all methods. Probability of detection analysis demonstrated no significant differences in the number of positive samples detected by the RapidChek method and the respective cultural reference method.


2019 ◽  
Vol 102 (5) ◽  
pp. 1589-1594
Author(s):  
Brooke Roman ◽  
Mark Mozola ◽  
Robert Donofrio ◽  
Benjamin Bastin ◽  
Nicole Klass ◽  
...  

Abstract Background: Listeria Right Now™ is a novel, enrichment-free test for the detection of Listeria spp. in swab samples taken from environmental surfaces. Results are available in less than 1 h. In a previous Performance Tested MethodSM (PTM) study, the test was validated for swab samples from stainless-steel and sealed concrete surfaces. Objective: A PTM matrix extension study was conducted to validate the method for the detection of Listeria spp. in swab samples from ceramic tile, plastic, and rubber surfaces. Methods: Performance of the Listeria Right Now method was compared to that of the U.S. Food and Drug Administration Bacteriological Analytical Manual reference culture procedure for the detection of Listeria spp. in swab samples taken from inoculated ceramic tile, plastic, and rubber surfaces. Data were analyzed using a probability of detection model. Results: There were no significant differences in performance between the Listeria Right Now and reference culture methods for any of the three surfaces tested, as determined by probability of detection analysis. Conclusions: The Listeria Right Now method is an effective procedure for the detection of Listeria spp. from a variety of environmental surfaces. Highlights: Listeria Right Now provides accurate results, without enrichment, in real time. This enables food industry personnel to react swiftly to suspected Listeria contamination incidents.


2013 ◽  
Vol 96 (4) ◽  
pp. 822-841 ◽  
Author(s):  
William Kwong ◽  
Kristin Livezey ◽  
Michael Reshatoff ◽  
Steve Vaughn ◽  
Anna Freed ◽  
...  

Abstract The Atlas™ Salmonella detection assay was compared to the reference culture methods for 12 foods and three surfaces. Comparison of the Atlas method to the U.S. Food and Drug Administration Bacteriological Analytical Manual (FDA/BAM) and U.S. Department of Agriculture-Food Safety and Inspection Service/Microbiology Laboratory Guidebook (USDA-FSIS/MLG) reference methods required an unpaired approach. Each method had a total of 320 samples inoculated with an S. enterica strain. Each food and surface was inoculated with a different strain of S. enterica at two different levels/method. Meat and egg products were compared to the USDA-FSIS/MLG 4.05 method. All other foods were compared to the FDA/BAM-5 method. The Atlas method had 148 positives out of 320 total inoculated samples, compared to 119 positives for the reference methods. Overall, the probability of detection analysis of the results showed equivalent or better performance by the Atlas Salmonella detection method compared to the reference methods. The Atlas Salmonella detection assay detected all 100 inclusive organisms and none of the 30 exclusive organisms. The lot-to-lot and kit stability studies showed no statistical differences between lots or over the term of the shelf-life. Instrument-to-instrument testing showed no statistical difference between instruments. Finally, the robustness study showed no difference when the sample volume added to the Atlas Salmonella detection assay varied by 10%, storage time was extended up to 5 days before analysis, or enrichment times were varied from 12 to 24 h.


1998 ◽  
Vol 120 (4) ◽  
pp. 365-373 ◽  
Author(s):  
F. A. Simonen ◽  
M. A. Khaleel

This paper describes probabilistic fracture mechanics calculations that simulate fatigue crack growth, flaw detection, flaw sizing accuracy, and the impacts of flaw acceptance criteria. The numerical implementation of the model is based on a Latin hypercube approach. Calculations have been performed for a range of parameters. For representative values of flaw detection probability, flaw sizing errors, and flaw acceptance criteria, detection capability is the most limiting factor with regard to the ability of the inservice inspections to reduce leak probabilities. However, gross sizing errors or significant relaxations of current flaw acceptance standards could negate the benefits of outstanding probability of detection capabilities.


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