Rapid Detection of Salmonellae in Foods Using Immunoassay Systems

1986 ◽  
Vol 49 (2) ◽  
pp. 92-98 ◽  
Author(s):  
GEORGE F. IBRAHIM ◽  
MARY J. LYONS ◽  
RETA A. WALKER ◽  
GRAHAM H. FLEET
Keyword(s):  
Solid Phase ◽  
False Negative ◽  
Food Samples ◽  
Negative Results ◽  
Cultural Method ◽  
False Negative Results ◽  
Salmonella Serotypes ◽  
Cost Efficient ◽  
Positive Results ◽  
Additional Sample

A standard cultural method, radioimmunometric (RIMA) and enzyme immunometric (EIMA) assays were compared for detection of salmonellae in 235 food samples. The immunoassays used titanous hydroxide as the solid-phase, commercial Spicer-Edwards salmonella polyvalent H antisera (SEA) or pooled antisera produced against 10 salmonella flagellins (PFA). Nineteen food samples were positive for Salmonella by the standard cultural method. These as well as one additional sample were also positive for Salmonella by RIMA and EIMA. No false-negative results were obtained from the immunoassays using PFA, whereas two false-negative results were observed when SEA was used. The incidence of false-positive results when SEA and PFA were used were, respectively, 3.0 and 0.9% with RIMA and 2.6 and 0.9% with EIMA. The immunoassays were also able to detect 77 Salmonella serotypes when grown alone or in association with other species of Enterobacteriaceae, in mannitol selenite cystine broth. Both immunoassays performed reliably on enrichment cultures stored under refrigeration for up to 9 d. Also, of 6 non-motile salmonellae, 5 were detectable by the immunoassays. The immunoassays were simple, rapid and cost-efficient.

Critical Evaluation of Impedance Phlebography for the Diagnosis of Deep Vein Thrombosis

1974 ◽  
Vol 31 (02) ◽  
pp. 273-278
Author(s):  
Kenneth K Wu ◽  
John C Hoak ◽  
Robert W Barnes ◽  
Stuart L Frankel
Keyword(s):  
Deep Vein Thrombosis ◽  
False Positive ◽  
False Negative ◽  
Critical Evaluation ◽  
Original Method ◽  
Vein Thrombosis ◽  
Negative Results ◽  
False Negative Results ◽  
Deep Vein ◽  
Positive Results

SummaryIn order to evaluate its daily variability and reliability, impedance phlebography was performed daily or on alternate days on 61 patients with deep vein thrombosis, of whom 47 also had 125I-fibrinogen uptake tests and 22 had radiographic venography. The results showed that impedance phlebography was highly variable and poorly reliable. False positive results were noted in 8 limbs (18%) and false negative results in 3 limbs (7%). Despite its being simple, rapid and noninvasive, its clinical usefulness is doubtful when performed according to the original method.

Thyroid Screening for Early Discharged Infants

PEDIATRICS ◽  
1996 ◽  
Vol 98 (1) ◽  
pp. 41-44
Author(s):  
Judy G. Saslow ◽  
Ernest M. Post ◽  
Carol A. Southard
Keyword(s):  
New Jersey ◽  
Congenital Hypothyroidism ◽  
False Positive ◽  
False Negative ◽  
Negative Results ◽  
Thyroid Screening ◽  
False Negative Results ◽  
Positive Results

Objective. As neonatal discharge before 24 hours of life becomes commonplace, the rejection of congenital hypothyroidism (CH) screening specimens obtained too early has created the need for numerous additional tests. We sought to determine whether the specimens obtained before 24 hours could be used safely. Methods. During a 31-day period we measured thyrotropin in all thyroid-screening specimens that had been obtained before 24 hours. We also examined the early specimens from every infant diagnosed in New Jersey with CH during 1993 or 1994. Results. Among the 663 specimens, those obtained at or before 12 hours and those from infants with birth weights less than 2500 g had too many low thyroxine results to be useful. Among the 515 specimens obtained at more than 12 to 24 hours from newborns weighing 2500 g or more, 37 (7%) had low thyroxine levels and 12 (2.3%) had thyrotropin levels of 20 µIU/mL (mU/L) or higher. Four hundred seventy-one of the 515 infants had subsequent specimens obtained at more than 24 hours, and none of the results were abnormal. There was no child weighing more than or equal to 2500 g who was diagnosed with CH in 1993 and 1994 whose specimen obtained at 24 hours or less was normal. Conclusions. Accepting specimens obtained at more than 12 to 24 hours from infants weighing 2500 g or more would have resulted in more than the usual number of false-positive results but no false-negative results. This would have decreased the requests for additional specimens by more than 90%.

Preenrichment Conditions for Effective Recovery of Salmonella in Foods and Feed Ingredients

1979 ◽  
Vol 42 (2) ◽  
pp. 153-157 ◽  
Author(s):  
J. Y. D'AOUST ◽  
C. MAISHMENT
Keyword(s):  
Brilliant Green ◽  
False Negative ◽  
Food Samples ◽  
Contamination Level ◽  
Experimental Conditions ◽  
Feed Ingredients ◽  
Selective Enrichment ◽  
Negative Results ◽  
False Negative Results ◽  
The Cost

The efficacy of Clausen, EE, Eugon, GN, Tergitol 7, lactose and nutrient broths as Salmonella preenrichment media was evaluated using 165 food samples with an incident contamination level ranging from 1.5 to 460 salmonellae/100 g. Replicate food samples (100 g) were preenriched in each of seven media (900 ml) for 6 h and 24 h at 35 C; various amounts (10, 1.0 and 0.1 ml) of preenriched cultures were selectively enriched in tetrathionate brilliant green (43 C) and selenite cystine (35 C) broths and plated on bismuth sulfite and brilliant green sulfa agars. Short (6 h) and 24-h preenrichment conditions resulted in 26 (16%) and 8 (5%) false negative results, respectively. Recovery of Salmonella from 6-h but not 24-h preenrichment cultures also varied directly with the portion of culture inoculated into selective enrichment broths. None of the preenrichment media tested performed satisfactorily at 6 h of incubation where levels of recovery ranged from 32 to 62%; at 24 h, good recovery was obtained with all media (95 to 100%) except EE broth (74%). The incidence of competitive flora was significantly higher on selenite + brilliant green sulfa than on tetrathionate + bismuth sulfite; transfer volumes (10 and 1.0 ml) and preenrichment media did not contribute significantly to the presence of non-salmonellae on plating media. Characteristics of preenrichment media were found to be less critical than preenrichment incubation time for effective recovery of Salmonella in foods and feed ingredients. The use of 1.0- rather than 10-ml preenrichment transfer volume is indicated because it proved to be completely reliable under our experimental conditions and reduced the cost of analyses.

Surfactants for the Effective Recovery of Salmonella in Fatty Foods

1982 ◽  
Vol 45 (3) ◽  
pp. 249-252 ◽  
Author(s):  
J.-Y. D'AOUST ◽  
C. MAISHMENT ◽  
P. STOTLAND ◽  
A. BOVILLE
Keyword(s):  
Salmonella Enteritidis ◽  
Brilliant Green ◽  
False Negative ◽  
Tween 80 ◽  
Food Samples ◽  
Nutrient Broth ◽  
Tween 20 ◽  
Negative Results ◽  
False Negative Results ◽  
Tween 60

Inhibitory concentrations of 8 surfactants were determined for Salmonella typhimurium and Salmonella enteritidis. Pure culture work resulted in the exclusion of Tween 20, Teepol 610 and Brij 35 and retention of Tergitol-7 (T-7), Tween 80 (TW 80), Triton X-100 (TX), Myrj 52S (M), and Arlacel 80 + Tween 60 (AT) for a study on the quantitative recovery of Salmonella in 45 naturally contaminated fatty foods. Replicate food samples (100 g) were preenriched overnight at 35 C in nutrient broth supplemented with 3%(w/v) surfactant except AT (10%). Serial dilutions of preenrichment cultures were selectively enriched overnight in tetrathionate brilliant green (43 C) and selenite cystine (35 C) broths and streaked on bismuth sulfite and brilliant green sulfa agar media. Recovery with all test surfactants was comparable to that obtained with nutrient broth controls; of 270 preenrichment cultures tested, only 7 false-negative results attributable to TX (3), AT (2), M (1), and nutrient broth control (1) were obtained. None of the surfactants consistently yielded greater populations of Salmonella for given foods or food categories; median counts for preenrichment cultures were 104–105 salmonellae/ml for low and high moisture foods and 106–107 salmonellae/ml for animal feeds. These results suggest that use of surfactants to facilitate detection of Salmonella in fatty foods is not warranted.

scholarly journals Validation of Two Commercial Lateral Flow Devices for the Detection of Peanut Proteins in Cookies: Interlaboratory Study

2006 ◽  
Vol 89 (2) ◽  
pp. 462-468 ◽  
Author(s):  
Arjon J van Hengel ◽  
Claudia Capelletti ◽  
Marcel Brohee ◽  
Elke Anklam ◽  
M-C S Baumgartner ◽  
...  
Keyword(s):  
False Negative ◽  
Lateral Flow ◽  
Food Matrix ◽  
Negative Results ◽  
False Negative Results ◽  
Test Kit ◽  
Interlaboratory Validation ◽  
Peanut Proteins ◽  
Flow Devices ◽  
Positive Results

Abstract Results are reported for an interlaboratory validation study of 2 commercially available lateral flow devices (dipstick tests) designed to detect peanut residues in food matrixes. The test samples used in this study were cookies containing peanuts at 7 different concentrations in the range of 030 mg peanuts/kg food matrix. The test samples with sufficient and proven homogeneity were prepared in our laboratory. The analyses of the samples (5 times per level by each laboratory) were performed by 18 laboratories worldwide, which submitted a total of 1260 analytical results. One laboratory was found to be an outlier for one of the test kits. In general, both test kits performed well. However, some false-negative results were reported for all matrixes containing <21 mg peanuts/kg cookie. It must be stressed that the test kits were challenged beyond their cut-off limits (5 mg/kg, depending on the food matrix). One test kit showed fewer false-negative results, but it led to some false-positive results for the blank materials. The sensitivity of the dipstick tests approaches that achieved with enzyme-linked immunosorbent assays.

scholarly journals Standardization of Estrogen Receptor Measurement in Breast Cancer Suggests False-Negative Results Are a Function of Threshold Intensity Rather Than Percentage of Positive Cells

2011 ◽  
Vol 29 (22) ◽  
pp. 2978-2984 ◽  
Author(s):  
Allison W. Welsh ◽  
Christopher B. Moeder ◽  
Sudha Kumar ◽  
Peter Gershkovich ◽  
Elaine T. Alarid ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
False Negative ◽  
Negative Results ◽  
False Negative Results ◽  
Threshold Assessment ◽  
Quantitative Immunofluorescence ◽  
Er Positive ◽  
Quantitative Immunoblotting ◽  
Positive Results

Purpose Recent misclassification (false negative) incidents have raised awareness concerning limitations of immunohistochemistry (IHC) in assessment of estrogen receptor (ER) in breast cancer. Here we define a new method for standardization of ER measurement and then examine both change in percentage and threshold of intensity (immunoreactivity) to assess sources for test discordance. Methods An assay was developed to quantify ER by using a control tissue microarray (TMA) and a series of cell lines in which ER immunoreactivity was analyzed by quantitative immunoblotting in parallel with the automated quantitative analysis (AQUA) method of quantitative immunofluorescence (QIF). The assay was used to assess the ER protein expression threshold in two independent retrospective cohorts from Yale and was compared with traditional methods. Results Two methods of analysis showed that change in percentage of positive cells from 10% to 1% did not significantly affect the overall number of ER-positive patients. The standardized assay for ER on two Yale TMA cohorts showed that 67.9% and 82.5% of the patients were above the 2-pg/μg immunoreactivity threshold. We found 9.1% and 19.7% of the patients to be QIF-positive/IHC-negative, and 4.0% and 0.4% to be QIF-negative/IHC-positive for a total of 13.1% and 20.1% discrepant cases when compared with pathologists' judgment of threshold. Assessment of survival for both cohorts showed that patients who were QIF-positive/pathologist-negative had outcomes similar to those of patients who had positive results for both assays. Conclusion Assessment of intensity threshold by using a quantitative, standardized assay on two independent cohorts suggests discordance in the 10% to 20% range with current IHC methods, in which patients with discrepant results have prognostic outcomes similar to ER-positive patients with concordant results.

scholarly journals False-Negative Results in Point-of-Care Qualitative Human Chorionic Gonadotropin (hCG) Devices Due to Excess hCGβ Core Fragment

2009 ◽  
Vol 55 (7) ◽  
pp. 1389-1394 ◽  
Author(s):  
Ann M Gronowski ◽  
Mark Cervinski ◽  
Ulf-Håkan Stenman ◽  
Alison Woodworth ◽  
Lori Ashby ◽  
...  
Keyword(s):  
Chorionic Gonadotropin ◽  
Human Chorionic Gonadotropin ◽  
Point Of Care ◽  
False Negative ◽  
The Core ◽  
Core Fragment ◽  
Negative Results ◽  
False Negative Results ◽  
Positive Results ◽  
Urine Specimens

Abstract Background: During pregnancy, human chorionic gonadotropin (hCG) immunoreactivity in urine consists of intact hCG as well as a number of hCG variants including the core fragment of hCGβ (hCGβcf). We identified 3 urine specimens with apparent false-negative results using the OSOM® hCG Combo Test (Genzyme Diagnostics) qualitative hCG device and sought to determine whether an excess of 1 of the fragments or variants might be the cause of the interference. Methods: We measured concentrations of hCG variants in the urine from 3 patients with apparent false-negative hCG results. Purified hCG variants were added to urines positive for hCG and tested using the OSOM, ICON® 25 hCG (Beckman Coulter), and hCG Combo SP® Brand (Cardinal Health) devices. Results: Dilution of these 3 urine samples resulted in positive results on the OSOM device. Quantification of hCG variants in each of the 3 patient urine specimens demonstrated that hCGβcf occurred in molar excess of intact hCG. Addition of purified hCGβcf to hCG-positive urines caused false-negative hCG results using the OSOM and ICON qualitative urine hCG devices. Conclusions: Increased concentrations of hCGβcf can cause false-negative results on the OSOM and ICON qualitative urine hCG devices. .

scholarly journals Identification of etiological agents of selected bacterial and viral infections based on serological tests

2018 ◽  
Vol 72 ◽  
pp. 1162-1178
Author(s):  
Aleksandra Lewandowicz-Uszyńska ◽  
Piotr Naporowski ◽  
Gerard Pasternak ◽  
Danuta Witkowska
Keyword(s):  
False Positive ◽  
Cellular Response ◽  
Bacterial Infections ◽  
Viral Infections ◽  
False Negative ◽  
Main Role ◽  
Serological Tests ◽  
Negative Results ◽  
False Negative Results ◽  
Positive Results

The human immune system’s response to infection is closely related with the type of pathogen. First, a rapid, metabolically inexpensive and non-specific innate immunity is induced, then a specific acquired immunity is activated. In bacterial infections caused by intracellular pathogens, the main role is played by cellular response. In infections caused by bacterial extracellular pathogens, a crucial role is played by antibodies. The clinical symptoms of bacterial and viral infections very often are similar, which is why diagnosing them based only on medical history and physical examination is insufficient. To identify the etiological factors of infections differentiating media, biochemical tests, molecular methods and serological tests are used. The detection of microorganisms or their genetic material can be performed within a short time after the occurrence of an infection. The detection of antibodies is possible only in the appropriate time called the serological window. In a serological diagnostic of infections there are problems with an appropriate interpretation of obtained results. Cross-reactivity can give false positive results for the diagnosis of Chlamydophila pneumonia infection. The problem with the detection of Borrelia burgdorferi infection can be caused by a simultaneous coinfection with different spirochetes, syphilis, mononucleosis or HIV. In serological diagnostics of bacterial infections, the administration of antibiotics to patients before taking serum samples can be responsible for false negative results. Another reason for such results can be a weak humoral response in infected patients. In viral infections, false positive results can be caused by a coinfection of different viruses, especially from the same family or by bacterial or protozoal coinfections or by autoimmune diseases. False-negative results in viral infections often are caused by the early phase of an infection. To properly recognize an etiological factor of infection it is necessary to use an appropriate method, precision of test and collect samples at the appropriate time.

THE DIAGNOSTIC POTENTIAL OF URINAY AND SERUM CYTOKERATINS FOR URINARY BLADDER CANCER

2021 ◽  
Author(s):  
GIORGI ADEISHVILI ◽  
MIKHEIL SHAVDIA ◽  
DAVID TABAGARI
Keyword(s):  
Initial Level ◽  
False Negative ◽  
Urinary Bladder Cancer ◽  
True Positive ◽  
Large Tumor ◽  
Negative Results ◽  
Diagnostic Potential ◽  
Tumor Focus ◽  
False Negative Results ◽  
Positive Results

In our opinion, the obtained results show that the level of UBC cytokeratin determined in urine reflects the destruction of tissue by the tumor to a greater extent with deep invasion and with large tumor sizes. We believe that a decrease in the sensitivity of the UBC test in detecting recurrence in patients after TUR, in comparison with the sensitivity of the UBC test in patients with BC prior to treatment, is associated with an initial level of cytodestruction in the relapse of BC. The level of serum cytokeratin TPA largely reflects the onset of metabolic changes in the tumor focus. It is the combination of UBC + TPA tests that gives rise to true-positive results and a reduction in false-negative results, which increases the sensitivity of the method.

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