Comparative Evaluation of Practical Functionality of Rapid Test Format Kits for Detection of Escherichia coli O157:H7 on Lettuce and Leafy Greens

2009 ◽  
Vol 72 (12) ◽  
pp. 2461-2470 ◽  
Author(s):  
C. B. D'LIMA ◽  
T. V. SUSLOW
Keyword(s):  
Escherichia Coli ◽  
False Negative ◽  
Rapid Test ◽  
Leafy Vegetables ◽  
Critical Threshold ◽  
Escherichia Coli O157 ◽  
Leafy Greens ◽  
Negative Results ◽  
Consumer Safety ◽  
False Negative Results

Multistate outbreaks of Escherichia coli O157:H7 infection in 2005 and 2006 associated with fresh and especially minimally processed produce greatly escalated the application of rapid pathogen detection systems to safety management in this food category. Pathogen testing was rapidly integrated into preharvest qualification for field lots, incoming raw produce, or final product. The raw produce and final product were incorporated into test-and-hold programs, typically within a 10-h time frame. To enhance consumer safety and provide guidance for the industry, an assessment of selected kits in comparison to a culture-based method was undertaken. Four primary kits were compared: the Neogen Reveal, SDI RapidChek, BioControl GDS O157, and Qualicon BAX O157 MP. Nine different leafy greens were freshly harvested and inoculated with a five-isolate mixture of E. coli O157:H7 at 10 CFU/25 g of sample, and cultures were enriched following the specified protocol. The PCR method was most consistent for identifying the presence of the inoculated pathogen in the shortest period of time. For the red-pigmented leafy vegetables red butter lettuce, curly endive, red lettuce, and lollo rosa, 13, 38, 88, and 100% false-negative results, respectively, were obtained with the immunoassays, but PCR detection was minimally affected. Immunoassays were negatively affected by delays in achieving critical threshold populations during the allowed enrichment period. Leafy green type, temperature abuse, and preharvest environment were unlikely to affect the results of PCR-based kits. Findings strongly suggest that product testing systems using 8-h detection cutoffs may give false-negative results. These issues become very important in high-throughput testing and retest protocols for presumptive pathogen-positive lots of produce.

Survival of Escherichia coli O157:H7 and Campylobacter jejuni in Bottled Purified Drinking Water under Different Storage Conditions

2011 ◽  
Vol 74 (2) ◽  
pp. 254-260 ◽  
Author(s):  
HAMZAH M. AL-QADIRI ◽  
XIAONAN LU ◽  
NIVIN I. AL-ALAMI ◽  
BARBARA A. RASCO
Keyword(s):  
Escherichia Coli ◽  
Drinking Water ◽  
Campylobacter Jejuni ◽  
Culture Media ◽  
False Negative ◽  
Storage Conditions ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Log Reduction ◽  
Negative Results

Survival of Escherichia coli O157:H7 and Campylobacter jejuni that were separately inoculated into bottled purified drinking water was investigated during storage at 22, 4, and −18°C for 5, 7, and 2 days, respectively. Two inoculation levels were used, 1 and 10 CFU/ml (102 and 103 CFU/100 ml). In samples inoculated with 102 CFU/100 ml, C. jejuni was not detectable (>2-log reduction) after storage under the conditions specified above. E. coli O157:H7 was detected on nonselective and selective media at log reductions of 1.08 to 1.25 after storage at 22°C, 1.19 to 1.56 after storage at 4°C, and 1.54 to 1.98 after storage at −18°C. When the higher inoculation level of 103 CFU/100 ml was used, C. jejuni was able to survive at 22 and 4°C, with 2.25- and 2.17-log reductions, respectively, observed on nonselective media. At these higher inoculation levels, E. coli O157:H7 was detectable at 22, 4, and −18°C, with log reductions of 0.76, 0.97, and 1.21, respectively, achieved on nonselective media. Additionally, E. coli O157:H7 showed significant differences in culturability (P < 0.05) on the nonselective and selective culture media under the different storage conditions, with storage at −18°C for 2 days being the treatment most inhibiting. The percentage of sublethal injury of E. coli O157:H7 ranged from ~33 to 75%, indicating that microbial examination of bottled water must be done carefully, otherwise false-negative results or underestimation of bacterial numbers could pose a health risk when low levels of pathogens are present.

Analysis of Fusarium toxins in grain via dust: a promising field of application for rapid test systems

2014 ◽  
Vol 7 (4) ◽  
pp. 465-477 ◽  
Author(s):  
M. Reichel ◽  
S. Staiger ◽  
S. Biselli
Keyword(s):  
Current Practice ◽  
Regression Line ◽  
False Negative ◽  
Rapid Test ◽  
Self Control ◽  
Dust Particles ◽  
Negative Results ◽  
Promising Tool ◽  
False Negative Results ◽  
Dust Sampling

On site, mycotoxin measurements shall enable rapid decisions on the acceptance or rejection of lots. Hence, results have to be available fast, easy to get and, first of all, reliable. An innovative approach using dust samples was tested for its fitness for on-site mycotoxin analyses of grain lots and compared to current practice in grain testing. To prove correlation between mycotoxin concentrations in dust and respective concentrations in grain, regression analyses were performed. To obtain data points, dust was sieved from grain and both samples were analysed. As the contamination of the overall sample and its dust particles correlated well (wheat: R2DON=0.85, R2ZEA=0.82; rye: R2DON=0.73), contaminations in the grain were predictable from concentrations determined in respective dust particles. For on-site analysis, common lateral flow devices (LFD) were evaluated for their suitability to detect deoxynivalenol (DON) in grain dusts. On site, grain and dust samples were taken during the unloading of trucks using a customised dust-sampler. In contrast to grain samples, no additional physical sample preparation or homogenisation step was needed for dust. Instead, the sample was directly extracted and analysed for DON using LFD. By means of the regression line DON concentrations in grain were predicted from dust results and compared to concentrations directly measured in grain samples. No false negative results were observed and a contaminated grain lot (<1000 ?g/ kg DON) could be clearly identified. Evidence for reduced measurement uncertainty compared to current practice at lower total measurement costs was given. In this way, the fitness for purpose of the new approach combining rapid analyses with dust sampling for on-site mycotoxin screening was shown. The innovative high-throughput technology has the potential to improve on-site mycotoxin measurements in terms of speed, sensitivity, manageability and reliability and thus is a promising tool for enhanced industrial self-control.

Be aware of Shiga-toxin 2f-producing Escherichia coli: case report and false-negative results with certain rapid molecular panels

2020 ◽  
Vol 98 (4) ◽  
pp. 115177
Author(s):  
Aurélie Cointe ◽  
André Birgy ◽  
Alice Pascault ◽  
Ferielle Louillet ◽  
Alice Dufougeray ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Case Report ◽  
Shiga Toxin ◽  
False Negative ◽  
Negative Results ◽  
False Negative Results

Utilization of Fluorogenic Assay for Rapid Detection of Escherichia coli in Acidic Fruit Juice

2002 ◽  
Vol 65 (12) ◽  
pp. 1943-1948 ◽  
Author(s):  
STEVEN PAO ◽  
CRAIG L. DAVIS ◽  
LORETTA M. FRIEDRICH ◽  
MICKEY E. PARISH
Keyword(s):  
Escherichia Coli ◽  
Fruit Juice ◽  
Uv Light ◽  
False Negative ◽  
Enzyme Reaction ◽  
Inhibitory Effect ◽  
Sample Sizes ◽  
Citrus Juice ◽  
Negative Results ◽  
False Negative Results

This study was undertaken to investigate interference by acids commonly found in fruit juice in Escherichia coli assays involving the use of 4-methylumbelliferyl-β-d-glucuronide (MUG) as a fluorogenic substrate for enzyme reaction. Fluorescence intensity was negatively correlated (P &lt; 0.001) with the volume of fresh citrus juice tested by the lauryl tryptose broth (LST)-MUG assay, and the permissible sample sizes were limited to 0.3 and 0.5 ml for fresh citrus juices with pHs of 3.3 and 3.9, respectively. In addition, false-negative results were visually observed under UV light when the E*Colite assay was used to test large volumes (5 to 10 ml per test) of fresh citrus juice or when the test broth used for the LST-MUG assay was supplemented with citric, malic, or tartaric acid at 2 to 4 g/liter. These results suggest that the size and pH of acidic samples should be controlled in MUG-based fluorogenic assays. The inhibitory effect on fluorescence was due to high acidity, which reduces fluorescence from 4-methylumbelliferone. Buffering improved the assays. When sodium bicarbonate was incorporated in the enrichment broth at 10 g/liter, the permissible sample sizes for fresh grapefruit juice (pH 3.1) increased from 0.3 to 1 ml for the LST-MUG (with 9.9 ml of broth) assay and from 3 to 10 ml for the E*Colite (with 99 ml of broth) assay.

Spatial Distribution of Salmonella, Escherichia coli O157:H7, and Other Bacterial Populations in Commercial and Laboratory-Scale Sprouting Mung Bean Beds

2005 ◽  
Vol 68 (12) ◽  
pp. 2510-2518 ◽  
Author(s):  
R. HORA ◽  
M. KUMAR ◽  
L. GARCIA ◽  
B. SCHUMACHER ◽  
J. ODUMERU ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Irrigation Water ◽  
Water Samples ◽  
Mung Bean ◽  
False Negative ◽  
Bacterial Populations ◽  
Negative Results ◽  
False Negative Results ◽  
Thermotolerant Coliforms ◽  
Microbiological Status

The reliability of testing spent irrigation water to assess the microbiological status of sprouting mung bean beds has been investigated. In commercial trials, the distribution of opportunistic contaminants within 32 bean sprout beds (25 kg of mung beans per bin) was assessed 48 h after germination. The prevalence of generic Escherichia coli, thermotolerant coliforms, and Aeromonas in sprouts (n = 288) was 5, 11, and 39%, respectively, and 57, 70, and 79% in the corresponding spent irrigation water samples (n = 96). Contamination was heterogeneously distributed within the seedbed. In laboratory trials, beans inoculated with a five-strain cocktail of either Salmonella or E. coli O157:H7 (103 to 104 CFU/g) were introduced (1 g/500 g of noninoculated seeds) at defined locations (top, middle, or base), and the beans were then sprouted for 48 h. When seeds inoculated with pathogens were introduced at the base or top of the seedbed, the pathogens were typically restricted to these sites and resulted in 44% of the spent irrigation water samples returning false-negative results. Introducing inoculated beans into the middle or at the presoak stage enhanced the distribution of both pathogens within the subsequent sprout bed and resulted in comparable levels recovered in spent irrigation water. The study demonstrated that even though screening a single sample of spent irrigation water is more reliable than testing sprouts directly, it does not provide an accurate assessment of the microbiological status of sprouting mung bean beds. Such limitations may be addressed by ensuring that bean batches are mixed prior to use and by taking spent irrigation water samples from multiple sites at the latter stages of the sprouting process.

scholarly journals COVID-19 – the challenge to treat a disease and not a positive RT-PCR test

Pharmacia ◽  
2021 ◽  
Vol 68 (1) ◽  
pp. 155-161
Author(s):  
Maria Georgieva Moneva-Sakelarieva ◽  
Yozlem Ali Kobakova ◽  
Petar Yordanov Atanasov ◽  
Danka Petrova Obreshkova ◽  
Stefka Achkova Ivanova ◽  
...  
Keyword(s):  
False Negative ◽  
Rapid Test ◽  
Rt Pcr ◽  
Negative Results ◽  
False Negative Results ◽  
Chest X Ray ◽  
Pulmonary Changes ◽  
Coagulation Status ◽  
Pcr Test

The new pandemic disease COVID is quick spread worldwide.The primary method used for diagnosing of COVID-19 is detecting viral nucleic acids. The main problem with RT-PCR test is the false negative results. The negative RT-PCR does not exclude a SARS-CoV-2 infection and this method should not be used as the only diagnostic criteria. The RT-PCR result does not change the complex treatment of the disease. The aim of the current study is to compare the four groups clinical cases of the different parameters: RT-PCR test, rapid test, clinical picture, laboratory tests as hematology, inflammatory markers, coagulation status and chemistry and imaging examinations: Chest X-ray at and Chest CT scan. Complex therapeutic approach has been implemented: antibiotic, inflammatory, anticoagulants, oxygen therapy, hepatoprotectors, antimycotics, fibrinolytics, probiotics, essential oils, vitamins. During the follow-up period, a tendency for significant reduction and resorption of the pulmonary changes on the CT scans has been seen.

Evaluation of a rapid fluorogenic method for the detection ofEscherichia coliin dairy products

1991 ◽  
Vol 58 (4) ◽  
pp. 477-483 ◽  
Author(s):  
Hassan R. Sarhan ◽  
Leslie R. Williams ◽  
Howard A. Foster
Keyword(s):  
Escherichia Coli ◽  
Klebsiella Pneumoniae ◽  
Dairy Products ◽  
Membrane Filtration ◽  
False Negative ◽  
Raw Milk ◽  
False Positive Reaction ◽  
Negative Results ◽  
False Negative Results ◽  
Soft Cheese

SummaryA rapid fluorogenic medium was evaluated for the detection ofEscherichia coliin dairy products. The medium was capable of detectingEsch. coliafter 7·5 h incubation at 41·5 °C. Samples of pasteurized milk (136), raw milk (63), soft cheese (60) and pasteurized cream (39) were examined with media based on 4-methylumbelliferyl-β-D-glucuronide (MUG-7) and Violet red bile agar and there were no significant differences between the numbers ofEsch. colidetected on the two media. MUG-7 medium had a specificity of 98·6% and the small number of organisms giving a false positive reaction were identified asKlebsiella pneumoniae. The incidence of false negative results was ∼2%. MUG-7 medium was suitable for pour plate, spread plate and membrane filtration methods. Possible applications of the method are discussed.

scholarly journals Evaluation of the COVID-19 IgG/IgM Rapid Test from Orient Gene Biotech

2020 ◽  
Vol 58 (8) ◽  
Author(s):  
Sarah Dellière ◽  
Maud Salmona ◽  
Marine Minier ◽  
Audrey Gabassi ◽  
Alexandre Alanio ◽  
...  
Keyword(s):  
Large Scale ◽  
False Negative ◽  
Rapid Test ◽  
Performance Characteristics ◽  
Serological Tests ◽  
Population Immunity ◽  
Negative Results ◽  
False Negative Results ◽  
High Level ◽  
Test Cassette

ABSTRACT While the coronavirus disease 2019 (COVID-19) pandemic has peaked in many countries already, the current challenge is to assess population immunity on a large scale. Many serological tests are available and require urgent independent validation. Here, we report performance characteristics of Orient Gene Biotech COVID-19 IgG/IgM Rapid Test Cassette (OG) and compare it to Abbott SARS-CoV-2 IgG immunoassay (ASIA). Patients (n = 102) with a positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reverse transcriptase PCR (RT-PCR) were tested. The patients were asymptomatic (n = 2) or had mild (n = 37) or severe symptoms requiring hospitalization in a medical unit (n = 35) or intensive care unit (n = 28). Specificity was evaluated for 42 patients with previous viral and parasitic diseases as well as a high level of rheumatic factor. The sensitivity of OG was 95.8% (95% confidence interval [CI95%], 89.6 to 98.8) for samples collected ≥10 days after the onset of symptoms, which was equivalent to the sensitivity of ASIA of 90.5% (CI95%, 82.8 to 95.6). OG uncovered six false-negative results of ASIA, of which two had only IgM with OG. Specificity was 100% (CI95%, 93.4 to 100) with both tests on samples, including patients infected with endemic coronavirus. Overall, OG performance characteristics indicate that the test is suitable for routine use in clinical laboratories, and its performance is equivalent to that of immunoassay. Testing OG on a larger asymptomatic population may be needed to confirm these results.

Multilaboratory Validation of a Luminex Microbead-Based Suspension Array for the Identification of the 11 Most Clinically Relevant Shiga Toxin–Producing Escherichia coli O Serogroups†

2013 ◽  
Vol 76 (5) ◽  
pp. 867-870 ◽  
Author(s):  
ANDREW LIN ◽  
JULIE A. KASE ◽  
MICHELLE M. MOORE ◽  
INSOOK SON ◽  
NELLY TRAN ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
High Throughput ◽  
Shiga Toxin ◽  
False Positive ◽  
Collaborative Study ◽  
False Negative ◽  
Robust Method ◽  
Suspension Array ◽  
Negative Results ◽  
False Negative Results

Rapid and high-throughput identification and serotyping of Shiga toxin–producing Escherichia coli (STEC) O serogroups is important for detecting, investigating, and controlling STEC infection outbreaks and removing hazardous products from commerce. A Luminex microbead-based suspension array has been developed to identify the 11 most clinically relevant STEC serogroups: O26, O45, O91, O103, O104, O111, O113, O121, O128, O145, and O157. Here we present results of a blinded multilaboratory collaborative study involving 10 participants from nine laboratories using 55 unknown strains. From the total 495 analyses, two false-positive and three false-negative results were obtained, indicating the assay to be a rapid, high-throughput, and robust method for identifying clinically relevant STEC serogroups.

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