Low Rate of False-Positive Results with Use of A Rapid HIV Test

2002 ◽  
Vol 23 (6) ◽  
pp. 335-337 ◽  
Author(s):  
Cassandra D. Salgado ◽  
Heidi L. Flanagan ◽  
Doris M. Haverstick ◽  
Barry M. Farr
Keyword(s):  
Enzyme Immunoassay ◽  
False Positive ◽  
Diagnostic System ◽  
Rapid Test ◽  
Occupational Exposures ◽  
High Rate ◽  
Negative Results ◽  
Hiv Test ◽  
Rapid Hiv Test ◽  
Positive Results

Background:Occupational exposure to human immunodeficiency virus (HIV) is an important threat to healthcare workers. Centers for Disease Control and Prevention guidelines recommend prompt institution of prophylaxis. This requires (1) immediate prophylaxis after exposure, pending test results that may take more than 24 hours in many hospitals; or (2) performance of a rapid test. The Single Use Diagnostic System (SUDS)® HIV-1 Test is used to screen rapidly for antibodies to HIV type 1 in plasma or serum, with a reported sensitivity of more than 99.9%. We used this test from January 1999 until September 2000, when it was withdrawn from the market following reports claiming a high rate of false-positive results.Methods:We reviewed the results of postexposure HIV testing during 21 months.Results:A total of 884 SUDS tests were performed on source patients after occupational exposures (883 negative results, 1 reactive result). The results of repeat SUDS testing on the reactive specimen were also reactive, but the results of enzyme immunoassay and Western blot testing were negative. A new specimen from the same patient showed a negative result on SUDS testing. This suggested a specificity of 99.9%. In the 4 months after SUDS testing was suspended, there was 1 false-positive result on enzyme immunoassay for 1 of 132 source patients (presumed specificity, 99.2%).Conclusion:Use of the SUDS test facilitated rapid and accurate evaluation of source specimens, obviating unnecessary prophylaxis.

scholarly journals False-Positive Results Obtained with the Alexon ProSpecT Cryptosporidium Enzyme Immunoassay

1999 ◽  
Vol 37 (5) ◽  
pp. 1582-1583 ◽  
Author(s):  
Kirk M. Doing ◽  
Jill L. Hamm ◽  
Jo Ann Jellison ◽  
Jessica A. Marquis ◽  
Cindy Kingsbury
Keyword(s):  
Enzyme Immunoassay ◽  
False Positive ◽  
Antigen Detection ◽  
Immunocompromised Patients ◽  
Careful Attention ◽  
Iodine Staining ◽  
Negative Results ◽  
Food Borne ◽  
Positive Results

Cryptosporidium is known to cause diarrhea in immunocompromised patients and is also associated with outbreaks of disease due to food-borne and waterborne parasites. Traditional procedures, involving iodine staining of wet mounts of stool sediments and trichrome staining, lack the sensitivity to detectCryptosporidium. Special staining procedures, such as the modified acid-fast and safranin stains, are generally employed. Less labor-intensive antigen detection assays have simplified detection; however, careful attention to local epidemiology is important because false-positive tests occur. Here, we report two incidents involving 62 false-positive results obtained with the Alexon ProSpecTCryptosporidium enzyme immunoassay, which were deemed false-positive based on negative results obtained from extensive microscopic examinations.

Emergency Department Management of Occupational Exposures: Cost Analysis of Rapid HIV Test

2001 ◽  
Vol 22 (5) ◽  
pp. 289-293 ◽  
Author(s):  
J. Celeste Kallenborn ◽  
Timothy G. Price ◽  
Ruth Carrico ◽  
Audrey B. Davidson
Keyword(s):  
Emergency Department ◽  
Occupational Exposure ◽  
Treatment Protocol ◽  
Rapid Test ◽  
Retrospective Chart Review ◽  
Occupational Exposures ◽  
Elisa Test ◽  
Enzyme Linked Immunosorbent Assay ◽  
Hiv Test ◽  
Rapid Hiv Test

AbstractObjective:To compare costs for evaluation and treatment of a healthcare worker (HCW) experiencing an occupational exposure, using a rapid human immunodeficiency virus (HIV) test versus a standard enzyme-linked immunosorbent assay (ELISA) HIV test.Design:Retrospective chart review of all HCWs presenting to the emergency department (ED) for care of an occupational exposure over a 13-month period.Setting:A 404-bed university-based level 1 trauma center with an annual ED census of approximately 35,000.Participants:All HCWs experiencing an occupational exposure treated in the ED using a rapid HPV protocol were included in the analysis.Methods:A calculation of selected costs of the initial evaluation and treatment of patients whose evaluation included a rapid HIV test on the source patient were performed. A similar calculation was then made for these patients, had the standard ELISA test been used. Evaluated costs included laboratory tests, postexposure prophylactic medications, and estimated lost work time. Other costs were constant and were not included in the evaluation.Results:Total evaluated cost using the rapid HIV test as part of the evaluation and treatment protocol was $465.80 for 17 patients. Had the ELISA test been used instead of the rapid test, the total evaluated cost for the 17 patients would have been $5,965.81.Conclusions:When used as part of the evaluation and treatment of the HCW with an occupational exposure, the rapid HIV test results in substantial cost savings over the ELISA test.

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%.

A Colony Blot Immunoassay for the Rapid Identification of Bacillus cereus

2004 ◽  
Vol 67 (2) ◽  
pp. 387-390 ◽  
Author(s):  
CHI-HUA CHEN ◽  
HWIA CHENG DING
Keyword(s):  
Horseradish Peroxidase ◽  
Cell Surface ◽  
Bacillus Cereus ◽  
False Positive ◽  
Rapid Identification ◽  
True Negative ◽  
Negative Results ◽  
Bacillus Spp ◽  
Positive Results ◽  
Peroxidase Conjugate

A colony blot immunoassay was developed for the rapid identification of Bacillus cereus using antibodies against the 28.5-kDa cell-surface antigen of B. cereus. Suspect colonies from plates were blotted onto a Whatman #541 membrane, dried, and fixed by UV irradiation. The membrane was then immersed in an anti- B. cereus antibody-horseradish peroxidase conjugate for 60 min. After washing and reacting with 4-chloro-1-naphthol and H2O2, the appearance of purple spots indicated the presence of B. cereus. This assay effectively identified 61 of 62 B. cereus strains tested. Among 38 non– B. cereus strains, which were other Bacillus spp. (19 genera), 36 gave true-negative results, and 2 showed false-positive results. The sensitivity and specificity for B. cereus were 98.4 and 94.7%, respectively. The present assay is easy to use, and the rapid identification of B. cereus can be completed in 2.5 h.

scholarly journals Assessment of Campylobacter fetus subsp. venerealis molecular diagnosis using clinical samples of bulls

2020 ◽  
Vol 16 (1) ◽  
Author(s):  
Marta Filipa Silva ◽  
Ana Duarte ◽  
Gonçalo Pereira ◽  
Luísa Mateus ◽  
Luís Lopes-da-Costa ◽  
...  
Keyword(s):  
False Positive ◽  
Bacterial Species ◽  
Venereal Disease ◽  
High Rate ◽  
Clinical Samples ◽  
Campylobacter Fetus ◽  
Subspecies Level ◽  
Geographical Regions ◽  
Pcr Assays ◽  
Positive Results

Abstract Background Campylobacter fetus subsp. venerealis (Cfv) is the pathogen responsible for Bovine Genital Campylobacteriosis (BGC), a venereal disease of cattle associated with impaired reproductive performance. Although several PCR assays were developed to identify this pathogen, most of them are still poorly evaluated in clinical samples. This study evaluated real-time PCR assays for Cfv detection in preputial samples of bulls (n = 308). Results The detection at the subspecies level (Cfv) compared four assays: two targeting ISCfe1 and two targeting parA gene. The detection at the species level (C. fetus) considered an assay targeting the nahE gene and a commercial kit for C. fetus identification. At the subspecies level, assays directed either to different targets (parA and ISCfe1), or to the same target (ISCfe1 or parA), showed a high percentage of disagreeing results. All samples positive at the subspecies level (n = 169) were negative in C. fetus detection assays, which strongly suggests the horizontal gene transfer of ISCfe1 and parA to other bacterial species. This was confirmed by microbiological isolation of three Campylobacter portucalensis strains responsible for false positive results. Sequences with a high level of identity with ISCfe1 and parA gene of Cfv were identified in C. portucalensis genome. Conclusions Overall, this study reveals that PCR assays solely directed to a subspecies target originate a high rate of false positive results, due to the presence of parA and ISCfe1 homologous sequences in other bacterial species, namely of the genus Campylobacter. Although the specificity of these methods may be higher if applied to bulls from herds with clinical features of BGC or in other geographical regions, current PCR diagnosis should couple subspecies and species targets, and further research must be envisaged to identify Cfv specific molecular targets.

scholarly journals False Positive Results in SARS-CoV-2 Serological Tests for Samples From Patients With Chronic Inflammatory Diseases

2021 ◽  
Vol 12 ◽  
Author(s):  
Nastya Kharlamova ◽  
Nicky Dunn ◽  
Sahl K. Bedri ◽  
Svante Jerling ◽  
Malin Almgren ◽  
...  
Keyword(s):  
Lupus Erythematosus ◽  
False Positive ◽  
Inflammatory Diseases ◽  
Serological Tests ◽  
Chronic Inflammatory Diseases ◽  
Negative Results ◽  
False Positive Signal ◽  
Lateral Flow Assays ◽  
Positive Results ◽  
Multiplex Bead

Patients with chronic inflammatory diseases are often treated with immunosuppressants and therefore are of particular concern during the SARS-CoV-2 pandemic. Serological tests will improve our understanding of the infection and immunity in this population, unless they tests give false positive results. The aim of this study was to evaluate the specificity of SARS-Cov-2 serological assays using samples from patients with chronic inflammatory diseases collected prior to April 2019, thus defined as negative. Samples from patients with multiple sclerosis (MS, n=10), rheumatoid arthritis (RA, n=47) with or without rheumatoid factor (RF) and/or anti-cyclic citrullinated peptide antibodies (anti-CCP2) and systemic lupus erythematosus (SLE, n=10) with or without RF, were analyzed for SARS-CoV-2 antibodies using 17 commercially available lateral flow assays (LFA), two ELISA kits and one in-house developed IgG multiplex bead-based assay. Six LFA and the in-house validated IgG assay correctly produced negative results for all samples. However, the majority of assays (n=13), gave false positive signal for samples from patients with RA and SLE. This was most notable in samples from RF positive RA patients. No false positive samples were detected in any assay using samples from patients with MS. Poor specificity of commercial serological assays could possibly be, at least partly, due to interfering antibodies in samples from patients with chronic inflammatory diseases. For these patients, the risk of false positivity should be considered when interpreting results of the SARS-CoV-2 serological assays.

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