Comparison of the BAX System PCR Method to Brazil's Official Method for the Detection of Salmonella in Food, Water, and Environmental Samples

A two-stage study compared the BAX system PCR method with the reference culture method used by the Brazilian Ministry of Agriculture and Food Supply for the detection of Salmonella in food, water, and environmental samples. In stage 1, fish matrix samples (n = 258) were spiked at several levels with Salmonella and a combination of Salmonella and non-Salmonella competitive organisms. Replicates were analyzed by the BAX system PCR method and the reference method with comparable results (sensitivity ≥ 97.5%, specificity ≥ 83.3%) from both methods at the limit of detection. In stage 2, a total of 1,988 samples with 70 product types were analyzed with both methods. Five laboratories were involved in this study, and the samples used were from routine analyses. The BAX system PCR method was shown to be comparable to the reference method, with a limit of detection of 1.0 to 2.0 CFU/25 g of sample. Analysis of the results obtained in stage 2 and in the combination of stages 1 and 2 for the BAX system showed the following performance: sensitivity ≥ 99.0%, specificity ≥ 97.2%, false-negative rate ≤ 1.1%, and false-positive rate ≤ 2.8%. Therefore, the BAX system appears to be equivalent to the reference method, with ≥ 97.3% agreement.

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Evaluation of an Immunomagnetic Separation–Real-Time PCR Assay for the Rapid Detection of Salmonella in Meat

Journal of Food Protection ◽

10.4315/0362-028x-69.12.2896 ◽

2006 ◽

Vol 69 (12) ◽

pp. 2896-2901 ◽

Cited By ~ 27

Author(s):

ANGELIKA NOTZON ◽

REINER HELMUTH ◽

JOHANN BAUER

Keyword(s):

Real Time ◽

Real Time Pcr ◽

False Positive Rate ◽

False Negative ◽

False Negative Rate ◽

Reference Method ◽

Immunomagnetic Separation ◽

Pcr Assay ◽

Positive Rate ◽

Meat Samples

The aim of this study was the comparison of an immunomagnetic separation (IMS)–real-time PCR assay for the detection of Salmonella with the cultural reference method according to §35 of the German Law on Food and Commodities (LMBG, L 00.00.20:1998). The IMS–real-time PCR assay includes a nonselective preenrichment step, an IMS, DNA extraction, as well as DNA purification followed by hybridization probe–based real-time PCR analysis. An accurate comparability was achieved, because both methods analyzed the same preenrichment. The evaluation was carried out using both artificially and naturally contaminated meat samples. The IMS–real-time PCR assay provides a result after 12 to 13 h. Compared with the reference method and regarding artificially contaminated meat samples, the IMS–real-time PCR assay achieved a specificity of 80% (false-positive rate of 20%) and a sensitivity of 100% (false-negative rate of 0%). The relative accuracy was 94%. The detection limit of both methods was 10 CFU/25 g. The concordance indexκ defines the statistical accordance, was 0.85 and indicated the agreement of both methods on statistical criteria. Compared to the reference method and analyzing naturally contaminated meat samples (n = 491), the IMS–real-time PCR assay showed a specificity of 99.3% (false-positive rate of 0.7%) and a sensitivity of 83.7% (false-negative rate of 16.3%). The relative accuracy was 98%. The concordance index κ had a value of 0.87 and highlighted the statistical agreement of both methods. In conclusion, the IMS–real-time PCR assay is suitable as specific, sensitive, and rapid screening method for the detection of Salmonella from meat.

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RapidChek SELECT Salmonella

Journal of AOAC International ◽

10.1093/jaoac/92.6.1890 ◽

2009 ◽

Vol 92 (6) ◽

pp. 1890-1894 ◽

Cited By ~ 8

Author(s):

Mark T Muldoon ◽

Jingkun Li ◽

Meredith Sutzko ◽

Ann Christine Olsson-Allen ◽

George Teaney ◽

...

Keyword(s):

False Positive Rate ◽

Peanut Butter ◽

False Negative ◽

False Negative Rate ◽

Reference Method ◽

Salmonella Spp ◽

Chi Square ◽

Negative Results ◽

Significant Difference ◽

Positive Rate

Abstract RapidChek SELECT Salmonella was previously validated in the Performance Tested MethodsSM program for the detection of Salmonella spp. in raw ground chicken, chicken carcass rinse, sliced cooked turkey, and liquid eggs. The present matrix extension study conducted under the AOAC Research Institute Emergency Response Validation program compared the RapidChek SELECT Salmonella method to the U.S. Food and Drug Administration's Bacteriological Analytical Manual (FDA-BAM) method for the detection of Salmonella Typhimurium in peanut butter. Overall, 27 samples were found positive by the RapidChek SELECT Salmonella method and 27 were found to be positive by the reference method. All RapidChek SELECT Salmonella presumptive positives were confirmed positive by the cultural reference method; additionally, all presumptive negative results were confirmed negative by the cultural reference method. Accordingly 0 false-negative rate and 0 false-positive rate were found. No significant difference between the RapidCheck SELECT Salmonella and FDA-BAM reference method was found; calculated Chi-square was 0. Results indicate that a low level of Salmonella in peanut butter can be successfully recovered and detected in the minimum 24 h enrichment protocol.

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Validation of the Legipid® Bioalarm Legionella Assay

Journal of AOAC International ◽

10.5740/jaoacint.12-146 ◽

2012 ◽

Vol 95 (5) ◽

pp. 1440-1451 ◽

Cited By ~ 3

Author(s):

Guillermo Rodríguez Albalat ◽

Begoña Bedrina Broch ◽

Marisa Jiménez Bono

Keyword(s):

Legionella Pneumophila ◽

Water Samples ◽

False Positive Rate ◽

False Negative ◽

False Negative Rate ◽

Reference Method ◽

Culture Method ◽

Magnetic Microspheres ◽

Test Volume ◽

Significant Difference

Abstract Legipid® Bioalarm Legionella is a test based on combined magnetic immunocapture and enzyme-immunoassay (CEIA) for the detection of Legionella pneumophila in water. Anti-L. pneumophila antibodies are immobilized on magnetic microspheres. Immunomagnetic analysis is applied to preconcentrated water samples in a final test volume of 9 mL. The method was compared with the standard culture method on both spiked and naturally contaminated water samples. The test was evaluated in potable, industrial, and natural water matrixes, according to the scope of the ISO 11731 reference method. These waters were tested with the target at levels ranging from low (10–99 CFU/mL) to high (100–999 CFU/mL); a Chi-square value of 1.8 indicated that there was no significant difference between the test and the reference method. The false-positive rate was 7%, and the false-negative rate 2%. For the inclusivity study, all 17 strains of L. pneumophila of different serogroups reacted with the test. For the exclusivity study, 17 strains of other Legionella species and 16 non-Legionella strains were tested. There were no cross-reactions with non-Legionella strains. L. beliardensis, L. adelaidensis, and one environmentally isolated Legionella sp. produced a positive result at high concentrations of 1800, 230, and 3900 CFU/mL, respectively. Agreement between the two methods was 95.9%.

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Singlepathr® Salmonella: Performance-Tested MethodSM 060401

Journal of AOAC International ◽

10.1093/jaoac/89.2.417 ◽

2006 ◽

Vol 89 (2) ◽

pp. 417-432 ◽

Cited By ~ 4

Author(s):

Lisa Thompson ◽

Charlotte Lindhardt ◽

Joseph Odumeru ◽

Joseph D Eifert

Keyword(s):

False Positive Rate ◽

False Negative ◽

False Negative Rate ◽

Reference Method ◽

Black Pepper ◽

Salmonella Spp ◽

Chi Square ◽

Qualitative Detection ◽

Significant Difference ◽

Positive Rate

Abstract Singlepath® Salmonella is an immunochromatographic (lateral flow) assay for the presumptive qualitative detection of Salmonella spp. in food. The AOAC Performance-Tested MethodSM study evaluated Singlepath Salmonella as an effective method for the detection of Salmonella spp. in the following selected foods: dried skimmed milk, black pepper, dried pet food, desiccated coconut, cooked peeled frozen prawns, raw ground beef, and raw ground turkey. When the foods were inoculated with Salmonella spp. at levels ranging from low 0.23–1.08 colony forming units (CFU)/25 g to high (2.3–6.0 CFU/25 g), a Chi-square value of 0.9 indicated that there was no significant difference between Singlepath Salmonella and the ISO 6579:2002 reference method. Singlepath Salmonella gave a false-positive rate of 7.3% and a false-negative rate of 2.5%. For the inclusivity study, all 105 Salmonella serovars reacted with Singlepath Salmonella. For the exclusivity study, 58 non-Salmonella spp. were tested. There were no cross-reactions with Singlepath Salmonella from these strains.

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Letters to the Editor

PEDIATRICS ◽

10.1542/peds.68.1.144a ◽

1981 ◽

Vol 68 (1) ◽

pp. 144-145

Author(s):

Lachlan Ch De Crespigny ◽

Hugh P. Robinson

Keyword(s):

Real Time ◽

Linear Array ◽

False Positive Rate ◽

False Negative ◽

False Negative Rate ◽

Letters To The Editor ◽

Premature Babies ◽

Computed Tomography Scans ◽

Positive Rate ◽

Time Linear

We read with interest the report which suggested that the diagnosis of cerebroventricular hemorrhage ([CVH] including both subependymal [SEH] and intraventricular) with real time ultrasound was unreliable.1 Ultrasound, when compared with computed tomography scans, had a 35% false-positive rate and a 21% false-negative rate. In our institution over a 12-month period more than 200 premature babies have been examined (ADR real time linear array scanner with a 7-MHz transducer).

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Pathologic Assessment of Computerized Tomography Accuracy for the Evaluation of the Laryngeal Cartilaginous Frame Work in Laryngopharyngeal Carcinomas

Tumori Journal ◽

10.1177/030089168907500216 ◽

1989 ◽

Vol 75 (2) ◽

pp. 156-162 ◽

Cited By ~ 5

Author(s):

Sandro Sulfaro ◽

Francesco Querin ◽

Luigi Barzan ◽

Mario Lutman ◽

Roberto Comoretto ◽

...

Keyword(s):

Computerized Tomography ◽

False Positive ◽

False Positive Rate ◽

False Negative ◽

False Negative Rate ◽

Cartilage Destruction ◽

High False Negative Rate ◽

Positive Rate ◽

Pathologic Assessment ◽

Low Sensitivity

Sixty-six whole-organ sectioned laryngopharyngectomy specimens removed for cancer during a seven-year period were uniformly examined to determine the accuracy of preoperative high resolution computerized tomography (CT) for detection of cartilaginous involvement. Our results indicate that CT has a high overall specificity (88.2%) but a low sensitivity (47.1 %); we observed a high false-negative rate (26.5%) and a fairly low false-positive rate (5.9%). Massive cartilage destruction was easily assessed by CT, whereas both small macroscopic and microscopic neoplastic foci of cartilaginous invasion were missed on CT scans. Moreover, false-positive cases were mainly due to proximity of the tumor to the cartilage. Clinical implications of these results are discussed.

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Macromolecule Particle Picking and Segmentation of a KLH Database by Unsupervised Cryo-EM Image Processing

Biomolecules ◽

10.3390/biom9120809 ◽

2019 ◽

Vol 9 (12) ◽

pp. 809

Author(s):

Miguel Carrasco ◽

Patricio Toledo ◽

Nicole D. Tischler

Keyword(s):

Signal To Noise Ratio ◽

False Positive Rate ◽

False Negative ◽

False Negative Rate ◽

Keyhole Limpet Hemocyanin ◽

True Positive Rate ◽

Cryo Electron Microscopy ◽

Positive Rate ◽

Top View ◽

Non Negative Matrix Factorization

Segmentation is one of the most important stages in the 3D reconstruction of macromolecule structures in cryo-electron microscopy. Due to the variability of macromolecules and the low signal-to-noise ratio of the structures present, there is no generally satisfactory solution to this process. This work proposes a new unsupervised particle picking and segmentation algorithm based on the composition of two well-known image filters: Anisotropic (Perona–Malik) diffusion and non-negative matrix factorization. This study focused on keyhole limpet hemocyanin (KLH) macromolecules which offer both a top view and a side view. Our proposal was able to detect both types of views and separate them automatically. In our experiments, we used 30 images from the KLH dataset of 680 positive classified regions. The true positive rate was 95.1% for top views and 77.8% for side views. The false negative rate was 14.3%. Although the false positive rate was high at 21.8%, it can be lowered with a supervised classification technique.

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Validity and Reliability of the Hooper Visual Organization Test

Perceptual and Motor Skills ◽

10.2466/pms.1974.39.1.95 ◽

1974 ◽

Vol 39 (1) ◽

pp. 95-100 ◽

Cited By ~ 13

Author(s):

Allan Gerson

Keyword(s):

False Positive Rate ◽

False Negative ◽

False Negative Rate ◽

Functional Disorders ◽

Validity And Reliability ◽

Clinical Value ◽

Clear Cut ◽

Positive Rate ◽

Organic Brain ◽

Visual Organization

To assess the validity and reliability of the Hooper Visual Organization Test, 68 Ss, of whom 16 were clinically and psychometrically determined to be suffering from organic brain damage, 19 had functional disorders, and 33 were without organic or functional disorders (normal), were given the test. The instrument was shown to be reliable ( r = .80), however, clear-cut discriminations between groups were not achieved. There were significant differences in scores of normal and damaged groups, functional and damaged Ss, but not functional and normal Ss. The qualitative signs said to aid in differentiations were totally absent from all protocols. Performance was affected in part by IQ and other aspects of recognition of meaning. There was a 19% false negative rate for the functionals and a 51% false positive rate for normals. The conclusion was that this device is of dubious clinical value.

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Empirical mean curve decomposition with multiwavelet transformation for eye movements recognition using electrooculogram signals

Proceedings of the Institution of Mechanical Engineers Part H Journal of Engineering in Medicine ◽

10.1177/0954411920924496 ◽

2020 ◽

Vol 234 (8) ◽

pp. 794-811

Author(s):

Harikrishna Mulam ◽

Malini Mudigonda

Keyword(s):

Neural Network ◽

Eye Movements ◽

False Positive Rate ◽

False Negative ◽

False Negative Rate ◽

Principal Component ◽

The Neural Network ◽

Marquardt Algorithm ◽

Positive Rate ◽

Sensitivity Specificity

Many research works are in progress in classification of the eye movements using the electrooculography signals and employing them to control the human–computer interface systems. This article introduces a new model for recognizing various eye movements using electrooculography signals with the help of empirical mean curve decomposition and multiwavelet transformation. Furthermore, this article also adopts a principal component analysis algorithm to reduce the dimension of electrooculography signals. Accordingly, the dimensionally reduced decomposed signal is provided to the neural network classifier for classifying the electrooculography signals, along with this, the weight of the neural network is fine-tuned with the assistance of the Levenberg–Marquardt algorithm. Finally, the proposed method is compared with the existing methods and it is observed that the proposed methodology gives the better performance in correspondence with accuracy, sensitivity, specificity, precision, false positive rate, false negative rate, negative predictive value, false discovery rate, F1 score, and Mathews correlation coefficient.

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Malicious Domain Names Detection Algorithm Based on N-Gram

Journal of Computer Networks and Communications ◽

10.1155/2019/4612474 ◽

2019 ◽

Vol 2019 ◽

pp. 1-9 ◽

Cited By ~ 2

Author(s):

Hong Zhao ◽

Zhaobin Chang ◽

Guangbin Bao ◽

Xiangyan Zeng

Keyword(s):

False Positive Rate ◽

False Negative ◽

False Negative Rate ◽

Detection Algorithm ◽

Internet Security ◽

Domain Name ◽

Domain Names ◽

Malicious Attack ◽

Positive Rate ◽

N Gram

Malicious domain name attacks have become a serious issue for Internet security. In this study, a malicious domain names detection algorithm based on N-Gram is proposed. The top 100,000 domain names in Alexa 2013 are used in the N-Gram method. Each domain name excluding the top-level domain is segmented into substrings according to its domain level with the lengths of 3, 4, 5, 6, and 7. The substring set of the 100,000 domain names is established, and the weight value of a substring is calculated according to its occurrence number in the substring set. To detect a malicious attack, the domain name is also segmented by the N-Gram method and its reputation value is calculated based on the weight values of its substrings. Finally, the judgment of whether the domain name is malicious is made by thresholding. In the experiments on Alexa 2017 and Malware domain list, the proposed detection algorithm yielded an accuracy rate of 94.04%, a false negative rate of 7.42%, and a false positive rate of 6.14%. The time complexity is lower than other popular malicious domain names detection algorithms.

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