Diagnosis ofClostridium difficileassociated diarrhea: comparison of three rapid methods employing different markers for detection

1995 ◽  
Vol 41 (1) ◽  
pp. 88-91 ◽  
Author(s):  
Kathleen M. Riederer ◽  
Patrick Lawson ◽  
Marilyn S. Held ◽  
Karen Petrylka ◽  
Laurence E. Briski ◽  
...  
Keyword(s):  
Clostridium Difficile ◽  
False Negative ◽  
Latex Agglutination ◽  
Cytotoxicity Assay ◽  
Test Results ◽  
Negative Results ◽  
False Negative Results ◽  
Hands On ◽  
Rapid Tests ◽  
Clostridium Difficile Associated Diarrhea

Latex agglutination and the enzyme immunoassays Cytoclone (EIA-C) and VIDAS (EIA-V) were compared with a cytotoxicity assay for the diagnosis of Clostridium difficile associated diarrhea. Among patients with discrepant results, the cytotoxicity assay and clinical assessment were used to evaluate the performance of the latex agglutination and EIA tests. Clostridium difficile associated diarrhea was documented in 30/149 samples (20.1%) from 130 patients. All test results matched in 113 instances. Latex agglutination, EIA-C, and EIA-V yielded false positive results in 10, 4, and 7 samples and false negative results in 8, 9, and 14 samples, respectively. Latex agglutination demonstrated 87.8% efficiency compared with 91.3% for EIA-C and 85.7% for EIA-V and 3 min hands-on time compared with 4.5 min for EIA-V and 10 min for EIA-C. On the basis of these findings and given the fact that all rapid tests have their shortcomings, we believe that latex agglutination is the most practical method.Key words: Clostridium difficile, diarrhea, colitis.

scholarly journals False Covid-19 Test Results – Could We Do Things Better? A Personal Opinion

2020 ◽  
Vol 8 (5) ◽  
Author(s):  
Suzanne Lisbeth Ekelund
Keyword(s):  
False Positive ◽  
False Negative ◽  
Test Results ◽  
Negative Results ◽  
False Negative Results ◽  
Personal Opinion ◽  
Potential Problems

This paper describes the problems with false covid-19 test results, both false positive and false negative results. The problems are related to the quality of tests, test sampling and the currently limited follow-up procedures. A test and follow-up strategy that could decrease the potential problems is suggested.

scholarly journals Comparative study of Allergy Explorer (ALEX) versus ImmunoCAP platforms

2020 ◽  
Vol 17 (1) ◽  
pp. 66-84
Author(s):  
C Nerelius ◽  
M Andersson ◽  
L Sogaard ◽  
M Schwanbeck ◽  
S Kofler ◽  
...  
Keyword(s):  
Dynamic Range ◽  
False Negative ◽  
Specific Ige ◽  
Test Results ◽  
Technical Performance ◽  
Negative Results ◽  
Allergen Components ◽  
False Negative Results ◽  
Low Dynamic Range ◽  
Immunocap Isac

Objective. In this study, technical performance of the new multiplex ALEX test was compared with results from ImmunoCAP single tests (tIgE, sIgE) and the multiplex platform ImmunoCAP ISAC sIgE 112. Materials and methods. Eleven whole allergen extracts and corresponding allergen components from different allergen groups were used for the analysis of 64-66 patients’ sera by all three platforms. Results. For the whole allergens, 55% false negative results were obtained with the ALEX test comparing to the ImmunoCAP sIgE tests while for allergen components the ALEX test gives 33% false negative results when compared to ImmunoCAP sIgE test results. Additionally, the ALEX test is characterized by a low dynamic range - the platform demonstrated no results above 36 kUA/L for samples giving >100 kUA/L using ImmunoCAP Specific IgE tests in the analysis of sIgE response to the whole allergens. For the allergen components, ALEX showed no results above 38 kUA/L for samples of up to 150 kUA/L according to ImmunoCAP Specific IgE test results. Comparing to ImmunoCAP single plex tests, ALEX show low dynamic range and poor agreement in quantitative results for tIgE and sIgE both for whole allergens and allergen components, while in the comparison with ImmunoCAP ISAC sIgE 112 platform, the agreement is better, but the sensitivity and dynamic range are still low._ Conclusions. The ALEX test has some serious limitations in its performance comparing to both types of ImmunoCAP platforms.

scholarly journals Comparative study of Allergy Explorer (ALEX) versus ImmunoCAP platforms

2020 ◽  
Vol 17 (1) ◽  
pp. 66-84
Author(s):  
C Nerelius ◽  
M Andersson ◽  
L Sogaard ◽  
M Schwanbeck ◽  
S Kofler ◽  
...  
Keyword(s):  
Dynamic Range ◽  
False Negative ◽  
Specific Ige ◽  
Test Results ◽  
Technical Performance ◽  
Negative Results ◽  
Allergen Components ◽  
False Negative Results ◽  
Low Dynamic Range ◽  
Immunocap Isac

Objective. In this study, technical performance of the new multiplex ALEX test was compared with results from ImmunoCAP single tests (tIgE, sIgE) and the multiplex platform ImmunoCAP ISAC sIgE 112. Materials and methods. Eleven whole allergen extracts and corresponding allergen components from different allergen groups were used for the analysis of 64-66 patients sera by all three platforms. Results. For the whole allergens, 55% false negative results were obtained with the ALEX test comparing to the ImmunoCAP sIgE tests while for allergen components the ALEX test gives 33% false negative results when compared to ImmunoCAP sIgE test results. Additionally, the ALEX test is characterized by a low dynamic range - the platform demonstrated no results above 36 kUA/L for samples giving 100 kUA/L using ImmunoCAP Specific IgE tests in the analysis of sIgE response to the whole allergens. For the allergen components, ALEX showed no results above 38 kUA/L for samples of up to 150 kUA/L according to ImmunoCAP Specific IgE test results. Comparing to ImmunoCAP single plex tests, ALEX show low dynamic range and poor agreement in quantitative results for tIgE and sIgE both for whole allergens and allergen components, while in the comparison with ImmunoCAP ISAC sIgE 112 platform, the agreement is better, but the sensitivity and dynamic range are still low._ Conclusions. The ALEX test has some serious limitations in its performance comparing to both types of ImmunoCAP platforms.

Recommendations for Validating Estrogen and Progesterone Receptor Immunohistochemistry Assays

2010 ◽  
Vol 134 (6) ◽  
pp. 930-935 ◽  
Author(s):  
Patrick L. Fitzgibbons ◽  
Douglas A. Murphy ◽  
M. Elizabeth H. Hammond ◽  
D. Craig Allred ◽  
Paul N. Valenstein
Keyword(s):  
Estrogen Receptor ◽  
Progesterone Receptor ◽  
Hormonal Therapy ◽  
False Negative ◽  
Test Results ◽  
Negative Results ◽  
False Negative Results ◽  
Technical Validation ◽  
Invasive Breast Carcinomas ◽  
Assessment Procedures

Abstract Context.—Estrogen receptor and progesterone receptor status is assessed on all newly diagnosed, invasive breast carcinomas and in recurrences to determine patient eligibility for hormonal therapy, but 10% to 20% of estrogen receptor and progesterone receptor test results are discordant when tested in multiple laboratories. Objective.—To define the analytic (technical) validation requirements for estrogen receptor and progesterone receptor immunohistochemistry assays used to select patients for hormonal therapy. Data Sources.—Literature review and expert consensus. Conclusions.—A standardized process for initial test validation is described. We believe adoption of this process will improve the accuracy of hormone-receptor testing, reduce interlaboratory variation, and minimize false-positive and false-negative results. Required ongoing assay assessment procedures are also described.

scholarly journals Negative Immunodiffusion Test Results Obtained with Sera of Paracoccidioidomycosis Patients May Be Related to Low-Avidity Immunoglobulin G2 Antibodies Directed against Carbohydrate Epitopes

2003 ◽  
Vol 10 (5) ◽  
pp. 802-807 ◽  
Author(s):  
Andréia R. Neves ◽  
Ronei L. Mamoni ◽  
Cláudio L. Rossi ◽  
Zoilo P. de Camargo ◽  
Maria Heloísa S. L. Blotta
Keyword(s):  
Paracoccidioides Brasiliensis ◽  
False Negative ◽  
Enzyme Linked Immunosorbent Assay ◽  
Test Results ◽  
Sodium Metaperiodate ◽  
Negative Results ◽  
Carbohydrate Epitopes ◽  
False Negative Results ◽  
Specific Igg

ABSTRACT Immunodiffusion (ID) is the serologic test most frequently used for the diagnosis and posttherapy follow-up of patients with paracoccidioidomycosis (PCM). The ID test is highly specific (100%), but its sensitivity is relatively low (90%), leading to false-negative results. The aim of this study was to determine the profiles of antibodies in sera from patients with proven PCM and with negative results in the ID test (IDneg) versus positive results in the ID test (IDpos). We analyzed 46 sera from patients with active PCM for total immunoglobulin G (IgG) and IgG subclass responses to Paracoccidioides brasiliensis gp43 antigen (treated or not treated with sodium metaperiodate) by enzyme-linked immunosorbent assay and immunoblotting. Immunoblotting showed that both IDneg and IDpos sera recognized predominantly the gp43 fraction of the P. brasiliensis antigen used in the ID test. IDneg sera contain low-avidity antibodies, low levels of specific IgG (total) and IgG1, and high levels of IgG2 compared with IDpos sera. The antibodies present in IDneg sera were predominantly directed against carbohydrate epitopes, since treatment with sodium metaperiodate resulted in a significant decrease in antibody reactivity. These data suggest that the lack of reactivity of sera from PCM patients in the ID test may be related to the production of low-avidity IgG2 antibodies directed against carbohydrate epitopes.

scholarly journals False Negative Results in Clostridium difficile Testing

2016 ◽  
Vol 16 (1) ◽  
Author(s):  
Yanal M. Murad ◽  
Justo Perez ◽  
Gustavo Ybazeta ◽  
Sarah Mavin ◽  
Sebastien Lefebvre ◽  
...  
Keyword(s):  
Clostridium Difficile ◽  
False Negative ◽  
Negative Results ◽  
False Negative Results

Evaluation and comparison of commercially available pregnancy tests based on monoclonal antibodies to human choriogonadotropin.

1986 ◽  
Vol 32 (12) ◽  
pp. 2166-2170 ◽  
Author(s):  
R Gelletlie ◽  
J B Nielsen
Keyword(s):  
False Positive ◽  
False Negative ◽  
Latex Agglutination ◽  
Negative Results ◽  
Human Choriogonadotropin ◽  
Specificity And Sensitivity ◽  
Beta Hcg ◽  
False Negative Results ◽  
Slide Test ◽  
High Concentrations

Abstract We evaluated eight pregnancy tests: Tandem Icon, beta-hCG Rapid, Pregnastick (immunoenzymometric assays), Neo-Pregnosticon (direct hemagglutination), Pregnospia (sol particle immunoassay), Neo-Planotest (latex agglutination), Gravindex beta-hCG, and beta-hCG Slide Test (both latex-agglutination inhibition), all of which detect human choriogonadotropin (hCG) in urine. We investigated the limits of detection and the responses to the following substances: human lutropin, protein, and blood, and high concentrations of hCG. Using 100 patients' samples, we assessed the diagnostic specificity and sensitivity as well as the accuracy of each kit. The detection limits for Tandem Icon, beta-hCG Rapid, Neo-Pregnosticon, Pregnospia, Neo-Planotest, and Gravindex beta-hCG were as stated by the manufacturers. Only Neo-Planotest gave a false-positive result for lutropin. The three immunoenzymometric assays were not affected by protein or blood, but of these only Tandem Icon did not exhibit prozoning. The five other kits gave false-positive or false-negative results for protein and blood. Tandem Icon performed best, being quick and easy to use and without susceptibility to interfering substances.

Mutation spectrum and erythrocyte indices characterisation of α-thalassaemia and β-thalassaemia in Sichuan women in China: a thalassaemia screening survey of 42 155 women

2020 ◽  
pp. jclinpath-2020-206588
Author(s):  
Bei Li ◽  
Xiao Han ◽  
Jian Ma ◽  
Dan Yang
Keyword(s):  
Southern China ◽  
False Negative ◽  
Mutation Spectrum ◽  
Test Results ◽  
Erythrocyte Indices ◽  
Negative Results ◽  
False Negative Results ◽  
High Prevalence ◽  
Mean Corpuscular Haemoglobin ◽  
Screening Survey

AimsThe present study aims to investigate the mutation spectrum of thalassaemia, and characterise the erythrocyte indices of thalassaemia in a large cohort in Sichuan, which is a province with a high prevalence of thalassaemia in southern China.MethodsThe present study was conducted from July 2017 to July 2019. A total of 42 155 women screened for thalassaemia were enrolled. The thalassaemia carriers were screened by erythrocyte analysis and haemoglobin electrophoresis. Then, the screening test results and genetic results were collected.ResultsA total of 1109 individuals had thalassaemia gene defects. Among these individuals, 69.7% were α-thalassaemia (α-thal) and 28.6% were β-thalassaemia (β-thal). For α-thal defects, carriers with --SEA had the lowest mean corpuscular volume (MCV) and mean corpuscular haemoglobin (MCH) values. For β-thal defects, carriers with heterozygous haemoglobin E and −28 had the highest MCV and MCH values. In addition, an MCV cut-off of 80 fl and an MCH cut-off of 27 pg was able to detect 99.1% α0 thalassaemia and 99.7% β0/β+ thalassaemia; however, that criterion could result in a great number of false-negative results in α+ carriers.ConclusionA criterion of MCV <80 fl and MCH <27 pg is recommended for detecting –SEA carriers and β0/β+ carriers, while higher cut-offs are needed to detect α+ carriers.

Urine drug-testing tampering approaches: Turkish probationers

2020 ◽  
pp. 002580242095645
Author(s):  
Melike Aydoğdu ◽  
Serap Annette Akgür
Keyword(s):  
Screening Test ◽  
Drug Testing ◽  
False Negative ◽  
Drug Abusers ◽  
Eye Drops ◽  
Test Results ◽  
Positive Ratio ◽  
Negative Results ◽  
False Negative Results ◽  
Urine Drug

The growing numbers of individual and social problems associated with drug abuse necessitate new approaches in drug-testing systems. Equally, drug abusers may attempt to invalidate drug testing using different methods such as adulteration, dilution and substitution. This study aims to investigate tampering methods commonly used by Turkish substance-using probationers and evaluate their effects on toxicological drug-testing results. Initially, probationer urinary screening test results and laboratory substitution documents were evaluated to investigate the dilution and substitution attempt. Additionally, an experimental study was carried out by using readily available household products (bleach, vinegar, drain opener, eye drops) for adulteration. The effect of these agents was investigated for 11‐nor‐9‐carboxy-Δ9‐tetrahydrocannabinol (THC–COOH), amphetamine and 3,4-methylenedioxymethamphetamine (MDMA). It was determined that probationers preferred unbranded products (syringes, nylon bottles, etc.) for urine substitution. To detect dilution, screening test results were evaluated along with creatinine values. The variability of mean creatinine values can change the rate of the before-negative and after-positive ratio. For adulteration method, the high amounts of bleach provided false-negative results for THC–COOH and amphetamine, but spiking in any concentration of bleach affected MDMA results, causing a slight increase. Vinegar did not affect the THC–COOH and amphetamine results. However, false-negative results were observed for MDMA, with high amounts of vinegar-spiked urine samples. Drain opener was added in large quantities, and false-negative results were observed for all analytes. Visine eye drops did not have any effect on THC–COOH or amphetamine, but a high quantity of eye drops had a slight decreasing effect for MDMA.

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