scholarly journals Qualitative Evaluation of Causes for Routine Salmonella Monitoring False-Positive Test Results in Dutch Poultry Breeding Flocks

2021 ◽  
Vol 9 (11) ◽  
pp. 2215
Author(s):  
Eduardo Costa ◽  
Armin Elbers ◽  
Miriam Koene ◽  
Andre Steentjes ◽  
Henk Wisselink ◽  
...  
Keyword(s):  
False Positive ◽  
Good Reason ◽  
Monitoring Program ◽  
Competent Authority ◽  
Qualitative Evaluation ◽  
Population Data ◽  
Cross Contamination ◽  
Test Results ◽  
False Positive Test ◽  
The Eu

The Salmonella monitoring program, as outlined in the EU Commission regulation 200/2010, asks for repeated sampling in order to ascertain progress in achievement of the EU target. According to Article 2.2.2.2.c of this regulation, the competent authority may decide to do a resample and retest when it has reasons to question the results of initial testing. In the Netherlands, the competent authorities have been resampling and retesting all initial positive samplings for several years because of doubts about false positive initial test results. An analysis of population data in the period 2015–2019 indicates that 48% of initial samplings at the farm were classified as false positive after resampling and retesting by the competent authorities. A qualitative analysis, assessing factors that could be associated with the occurrence of false positives, indicates that cross-contamination during the sampling process by the poultry farmer is probably the most likely source. Cross-contamination of samples during transport from the farm to the laboratory and/or cross-contamination at the laboratory are also considered possible sources. Given the slightly non-optimal system-specificity of the Salmonella monitoring program, there is good reason to make, or consider, standard resampling and retesting of initial positive results by the competent veterinary authorities possible within the EU.

Effects of organic acids and common household products on the occurrence of false positive test results using immunochromatographic assays

2020 ◽  
Vol 308 ◽  
pp. 110165
Author(s):  
Megan M. Foley ◽  
Catherine O. Brown ◽  
Christian G. Westring ◽  
Phillip B. Danielson ◽  
Heather E. McKiernan
Keyword(s):  
Organic Acids ◽  
False Positive ◽  
Positive Test ◽  
Test Results ◽  
False Positive Test ◽  
Household Products

False-Positive Test Results in a Patient With Severe Hepatitis

2015 ◽  
Vol 175 (2) ◽  
pp. 161
Author(s):  
Simina R. Luca ◽  
Mandana Kayedi ◽  
Brian M. Wong
Keyword(s):  
False Positive ◽  
Positive Test ◽  
Test Results ◽  
Severe Hepatitis ◽  
False Positive Test

H1N1 vaccination and false-positive test results for hepatitis B core antibody in health workers

Transfusion ◽  
2011 ◽  
Vol 51 (7) ◽  
pp. 1595-1596
Author(s):  
Patrícia R. Araújo ◽  
Guilherme A. Albertoni ◽  
Silvia R. Rizzo ◽  
Fabrício O. Carvalho ◽  
José A. Barreto
Keyword(s):  
Hepatitis B ◽  
False Positive ◽  
Health Workers ◽  
Positive Test ◽  
Test Results ◽  
False Positive Test

scholarly journals False-Positive Gen-Probe Direct Mycobacterium tuberculosis Amplification Test Results for Patients with Pulmonary M. kansasii and M. aviumInfections

1999 ◽  
Vol 37 (1) ◽  
pp. 175-178 ◽  
Author(s):  
James H. Jorgensen ◽  
Jesse R. Salinas ◽  
Rosemary Paxson ◽  
Karen Magnon ◽  
Jan E. Patterson ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
False Positive ◽  
Disease Patient ◽  
The United States ◽  
Positive Test ◽  
Test Results ◽  
High Power Field ◽  
Low Level ◽  
False Positive Test ◽  
Abnormal Chest

The Gen-Probe Amplified Mycobacterium Tuberculosis Direct (MTD) test has been approved for use in the United States for the rapid diagnosis of pulmonary tuberculosis in patients with acid-fast smear-positive sputum samples since 1996. Four patients infected with human immunodeficiency virus and one chronic pulmonary-disease patient seen in our institutions with abnormal chest radiographs and fluorochrome stain-positive sputa were evaluated for tuberculosis, including performance of the MTD test on expectorated sputum samples. Three of these five patients’ sputa were highly smear-positive (i.e., more than 100 bacilli per high-power field), while two patient’s sputa contained 1 to 10 bacilli per field. MTD results on sputum specimens from these patients ranged from 43,498 to 193,858 relative light units (RLU). Gen-Probe has defined values of at least 30,000 RLU as indicative of a positive test, i.e., the presence ofMycobacterium tuberculosis RNA. Four of the patients’ sputum cultures yielded growth of M. kansasii within 6 to 12 days, and the fifth produced growth of M. avium only. One patient’s culture contained both M. kansasii andM. avium, but none of the initial or follow-up cultures from these five patients revealed M. tuberculosis. However, subsequent cultures from three of the patients again revealed M. kansasii. During the period of this study, in which MTD tests were performed on smear-positive sputum specimens from 82 patients, four of seven patients with culture-proven M. kansasiipulmonary infections yielded one or more false-positive MTD tests. The MTD sensitivity observed in this study was 93.8%, and the specificity was 85.3%. Five cultures of M. kansasii (including three of these patients’ isolates and M. kansasii ATCC 12478), and cultures of several other species were examined at densities of 105 to 107 viable CFU/ml by the MTD test. All five isolates of M. kansasii and three of three isolates ofM. simiae yielded false-positive test results, with readings of 75,191 to 335,591 RLU. These findings indicate that low-level false-positive MTD results can occur due to the presence ofM. kansasii, M. avium, and possibly otherMycobacterium species other than M. tuberculosis in sputum. Low-level positive MTD results of 30,000 to 500,000 RLU should be interpreted in light of these findings. It remains to be determined if the enhanced MTD test (MTD 2) recently released by Gen-Probe will provide greater specificity than that observed in this report with its first-generation test.

scholarly journals Robustness of Serologic Investigations for Chikungunya and Mayaro Viruses following Coemergence

mSphere ◽  
2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Carlo Fischer ◽  
Fernando Bozza ◽  
Xiomara Jeanleny Merino Merino ◽  
Celia Pedroso ◽  
Edmilson F. de Oliveira Filho ◽  
...  
Keyword(s):  
Latin America ◽  
False Positive ◽  
Chikungunya Virus ◽  
Cross Reactivity ◽  
Positive Test ◽  
Antibody Detection ◽  
Test Results ◽  
Specific Patient ◽  
False Positive Test ◽  
Mayaro Virus

ABSTRACT Since 2013, the arthropod-borne Chikungunya virus (CHIKV) has cocirculated with the autochthonous Mayaro virus (MAYV) in Latin America. Both belong to the same alphavirus serocomplex, termed the Semliki Forest serocomplex. The extent of antibody cross-reactivity due to the antigenic relatedness of CHIKV and MAYV in commonly used serologic tests remains unclear. By testing 64 CHIKV- and 37 MAYV-specific sera from cohort studies conducted in Peru and Brazil, we demonstrate about 50% false-positive test results using commercially available enzyme-linked immunosorbent assays (ELISAs) based on structural antigens. In contrast, combining ELISAs for CHIKV and MAYV significantly increased positive predictive values (PPV) among all cohorts from 35.3% to 88.2% for IgM and from 61.3% to 96.8% for IgG (P < 0.0001). Testing of longitudinally collected CHIKV-specific patient sera indicated that ELISA specificity is highest for IgM testing at 5 to 9 days post-onset of symptoms (dpo) and for IgG testing at 10 to 14 dpo. IgG cross-reactivity in ELISA was asymmetric, occurring in 57.9% of MAYV-specific sera compared to 29.5% of CHIKV-specific sera. Parallel plaque reduction neutralization testing (PRNT) for CHIKV and MAYV increased the PPV from 80.0% to 100% (P = 0.0053). However, labor-intense procedures and delayed seroconversion limit PRNT for patient diagnostics. In sum, individual testing for CHIKV or MAYV only is prone to misclassifications that dramatically impact patient diagnostics and sero-epidemiologic investigation. Parallel ELISAs for both CHIKV and MAYV provide an easy and efficient solution to differentiate CHIKV from MAYV infections. This approach may provide a template globally for settings in which alphavirus coemergence imposes similar problems. IMPORTANCE Geographically overlapping transmission of Chikungunya virus (CHIKV) and Mayaro virus (MAYV) in Latin America challenges serologic diagnostics and epidemiologic surveillance, as antibodies against the antigenically related viruses can be cross-reactive, potentially causing false-positive test results. We examined whether widely used ELISAs and plaque reduction neutralization testing allow specific antibody detection in the scenario of CHIKV and MAYV coemergence. For this purpose, we used 37 patient-derived MAYV-specific sera from Peru and 64 patient-derived CHIKV-specific sera from Brazil, including longitudinally collected samples. Extensive testing of those samples revealed strong antibody cross-reactivity in ELISAs, particularly for IgM, which is commonly used for patient diagnostics. Cross-neutralization was also observed, albeit at lower frequencies. Parallel testing for both viruses and comparison of ELISA reactivities and neutralizing antibody titers significantly increased diagnostic specificity. Our data provide a convenient and practicable solution to ensure robust differentiation of CHIKV- and MAYV-specific antibodies.

Sign in / Sign up

Export Citation Format

Share Document