scholarly journals Most but not all laboratories can detect the recently emerged Neisseria gonorrhoeae porA mutants – results from the QCMD 2013 N. gonorrhoeae external quality assessment programme

2014 ◽  
Vol 19 (8) ◽  
Author(s):  
D Luijt ◽  
C Di Lorenzo ◽  
A M van Loon ◽  
M Unemo
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Quality Assessment ◽  
External Quality Assessment ◽  
False Negative ◽  
Molecular Diagnostic ◽  
External Quality ◽  
Diagnostic Assays ◽  
Assessment Programme ◽  
Negative Results ◽  
False Negative Results

We describe the results of the Quality Control for Molecular Diagnostics 2013 Neisseria gonorrhoeae external quality assessment programme that included an N. gonorrhoeae strain harbouring an N. meningitidis porA gene which causes false-negative results in molecular diagnostic assays targeting the gonococcal porA pseudogene. Enhanced awareness of the international transmission of such gonococcal strains is needed to avoid false-negative results in both in-house and commercial molecular diagnostic assays used in laboratories worldwide, but particularly in Europe.

External quality assessment scheme for parasite serology; a review of the scheme design and performance

2010 ◽  
Vol 63 (5) ◽  
pp. 441-444 ◽  
Author(s):  
S Collier ◽  
M Manser ◽  
P L Chiodini
Keyword(s):  
Quality Assessment ◽  
External Quality Assessment ◽  
False Negative ◽  
Parasitic Infection ◽  
External Quality ◽  
External Quality Assessment Scheme ◽  
Common Error ◽  
Scheme Design ◽  
Negative Results ◽  
And Performance

BackgroundAn external quality assessment (EQA) scheme for parasite serology was introduced in April 2005 as a tool to measure how well laboratories were performing in parasite serodiagnosis.Aim and MethodsTo review the scheme design and performance from its beginning until January 2008.ResultsThe numbers of participating laboratories gradually increased during the review period and was 28 in January 2008. The results showed that the standard of reporting was extremely high and there was an encouraging trend towards improvement in the overall percentage of correct reports. The most common error made was the returning of false negative results for Strongyloides antibodies.ConclusionIt is hoped that this scheme will lead to a more standardised approach to the serological diagnosis of parasitic infection.

scholarly journals The versatility of external quality assessment for the surveillance of laboratory and in vitro diagnostic performance: SARS-CoV-2 viral genome detection in Austria

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Christoph Buchta ◽  
Jeremy V. Camp ◽  
Jovana Jovanovic ◽  
Peter Chiba ◽  
Elisabeth Puchhammer-Stöckl ◽  
...  
Keyword(s):  
Quality Assessment ◽  
External Quality Assessment ◽  
False Negative ◽  
Positive Sample ◽  
Performance Criteria ◽  
External Quality ◽  
Assay Sensitivity ◽  
Dilution Series ◽  
Test Systems

Abstract Objectives External quality assessment (EQA) schemes provide information on individual and general analytical performance of participating laboratories and test systems. The aim of this study was to investigate the use and performance of SARS-CoV-2 virus genome detection systems in Austrian laboratories and their preparedness to face challenges associated with the pandemic. Methods Seven samples were selected to evaluate performance and estimate variability of reported results. Notably, a dilution series was included in the panel as a measure of reproducibility and sensitivity. Several performance criteria were evaluated for individual participants as well as in the cohort of all participants. Results A total of 109 laboratories participated and used 134 platforms, including 67 different combinations of extraction and PCR platforms and corresponding reagents. There were no false positives and 10 (1.2%) false negative results, including nine in the weakly positive sample (C t ∼35.9, ∼640 copies/mL). Twenty (22%) laboratories reported results of mutation detection. Twenty-five (19%) test systems included amplification of human RNA as evidence of proper sampling. The overall linearity of C t values from individual test systems for the dilution series was good, but inter-assay variability was high. Both operator-related and systematic failures appear to have caused incorrect results. Conclusions Beyond providing certification for participating laboratories, EQA provides the opportunity for participants to evaluate their performance against others so that they may improve operating procedures and test systems. Well-selected EQA samples offer additional inferences to be made about assay sensitivity and reproducibility, which have practical applications.

scholarly journals Detection of LytA Genes in Streptococcus pneumoniae Isolated from sputum pneumonia patients

Biomedika ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 23-30
Author(s):  
Mustika Sari Hutabarat ◽  
Firdaus Hamid ◽  
Irawaty Djaharuddin ◽  
Alfian Zainuddin ◽  
Rossana Agus ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
False Negative ◽  
Pneumococcal Infection ◽  
Diagnostic Methods ◽  
Molecular Diagnostic ◽  
Clinical Samples ◽  
Biochemical Tests ◽  
Negative Results ◽  
False Negative Results ◽  
Polymerase Chain

Streptococcus pneumoniae (pneumococcus) is a Gram-positive facultative anaerobic bacterium that is a major cause of morbidity and mortality worldwide. But the lack of reporting of disease by this bacterium in Indonesia, one of the causes is because the diagnosis of pneumococcal infection is often clinically not typical and conventional methods which are still the standard gold method often give false-negative results. So the purpose of this study was to evaluate the performance of culture and molecular diagnostic methods using the Polymerase Chain Reaction (PCR) technique in detecting Streptococcus pneumoniae in sputum clinical samples using the Autolysin (LytA) gene which is a virulence factor of this bacterium. 57 isolates from 60 samples were confirmed as Streptococcus sp through microscopic identification, culture, and biochemical tests. Then the sensitivity test with an optochin test of 9 (9%) compared the results descriptively with the PCR technique using the Autolysin A (LytA) gene which was obtained more sensitive by 15 (25%).

scholarly journals Clinical Neisseria gonorrhoeae isolate with a N. meningitidis porA gene and no prolyliminopeptidase activity, Sweden, 2011 – danger of false-negative genetic and culture diagnostic results

2012 ◽  
Vol 17 (9) ◽  
Author(s):  
D Golparian ◽  
E Johansson ◽  
M Unemo
Keyword(s):  
Neisseria Gonorrhoeae ◽  
False Negative ◽  
Gonorrhoeae Strain ◽  
Negative Results ◽  
False Negative Results ◽  
Gonorrhoeae Isolate

We describe a Neisseria gonorrhoeae strain, found in Sweden in 2011, that harbours a N. meningitidis porA gene causing false-negative results in PCRs targeting the gonococcal porA pseudogene. Furthermore, the strain had no prolyliminopeptidase (PIP) activity that many commercial biochemical kits for species verification in culture rely on. Enhanced awareness of the spread of such strains and screening for them can be crucial.

scholarly journals Towards Multitarget Testing in Molecular Microbiology

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Deborah Steensels ◽  
Anne Vankeerberghen ◽  
Hans De Beenhouwer
Keyword(s):  
False Negative ◽  
Lessons Learned ◽  
Patient Treatment ◽  
Culture Methods ◽  
Diagnostic Assays ◽  
Genome Variability ◽  
Negative Results ◽  
Conventional Culture ◽  
False Negative Results ◽  
Single Target

Advantages of PCR assays over more conventional culture-based diagnostics include significantly higher sensitivities and shorter turnaround times. They are particularly useful when patient treatment has already been initiated or for specimens that may contain microorganisms that are slow-growing, difficult to culture, or for which culture methods do not exist. However, due to genome variability, single target testing might lead to false-negative results. This paper focuses on examples from our own experiences and the literature to provide insight into the limitations of single target testing in molecular biology. Lessons learned from these experiences include the careful design of diagnostic assays, preferably multitargeted, the importance of investigating the incidence and epidemiology of infection in detail, the frequent participation in appropriate quality assurance schemes, and the importance of continuous attentiveness by investigators when confronted with inconsistent results. In conclusion, multitargeted testing in microbiological molecular assays should be a rule.

Prevalence of porA pseudogene deletion among Neisseria gonorrhoeae isolates referred to the UK’s Gonococcal Resistance to Antimicrobials Surveillance Program

Sexual Health ◽  
2017 ◽  
Vol 14 (4) ◽  
pp. 392 ◽  
Author(s):  
Martina Toby ◽  
Pamela Saunders ◽  
Michelle Cole ◽  
Vlad Grigorjev ◽  
Sarah Alexander ◽  
...  
Keyword(s):  
Neisseria Gonorrhoeae ◽  
False Negative ◽  
Public Health Problem ◽  
Surveillance Program ◽  
Major Public Health Problem ◽  
Negative Results ◽  
False Negative Results ◽  
Confirmatory Tests ◽  
Polymerase Chain ◽  
Low Prevalence

porA pseudogene-negative Neisseria gonorrhoeae isolates produce false-negative results when examined by polymerase chain reaction (PCR) with porA pseudogene targets. In the present study, 533 representative gonococcal isolates received in 2011 via the Gonococcal Resistance to Antimicrobials Surveillance Program were examined to determine the prevalence of porA-negative isolates. Less than 0.4% (2/533) of isolates were found to be reproducibly negative with the porA real-time PCR but were confirmed as N. gonorrhoeae with molecular, biochemical and immunological confirmatory tests. Sequencing revealed both isolates contained the Neisseria meningitidis porA gene. Low prevalence indicates that although these isolates do not present a major public health problem, microbiologists should remain vigilant.

scholarly journals External quality assessment for molecular diagnostic laboratories in Belgium: Can we improve it?

2019 ◽  
Vol 25 (1) ◽  
pp. 39-49
Author(s):  
Kelly Dufraing ◽  
Els Lierman ◽  
Anne Vankeerberghen ◽  
Sabine Franke ◽  
Els Dequeker
Keyword(s):  
Quality Assessment ◽  
Performance Monitoring ◽  
External Quality Assessment ◽  
Molecular Diagnostic ◽  
Real Patient ◽  
External Quality ◽  
Molecular Tests ◽  
Clinical Biology ◽  
Eqa Schemes ◽  
Selection Of

AbstractExternal quality assessment (EQA) is an essential part of performance monitoring for molecular laboratories. At the moment, a national law regulates participation in EQA schemes for clinical biology and pathology in Belgium. This study aimed (1) to get insights on how laboratories organize their EQA participation, (2) to poll satisfaction with the current situation (selection of EQA programs in advance by a governmental body), (3) to provide guidance for choosing the most relevant EQA provider and (4) to propose a new model for national performance monitoring. A survey was sent to Belgian laboratories performing molecular tests in the field of microbiology, hematology and pathology with (1) general questions on how they select an EQA provider and (2) their satisfaction of each provider. In total, 25 molecular laboratories [microbiology (N = 13), hematology (N = 8) and pathology (N = 4)] from 14 different hospitals completed the survey regarding their EQA organization. All three laboratory groups indicated to prefer EQA schemes using real patient materials as well as those with varying targets and concentrations. For molecular microbiology and hematology, schemes with a syndromic approach are sought. Since annual participation in EQA becomes burdensome in most laboratories, this paper also offers a risk-based strategy for determining the participation frequency. Based on the needs of Belgian laboratories, three proposals were made: (1) for the proper selection of an EQA scheme, (2) for determining the minimal participation frequency and (3) for the national organization of EQA schemes.

scholarly journals Benchmark for Evaluating the Quality of DNA Sequencing: Proposal from an International External Quality Assessment Scheme

2006 ◽  
Vol 52 (4) ◽  
pp. 728-736 ◽  
Author(s):  
Simon J Patton ◽  
Andrew J Wallace ◽  
Rob Elles
Keyword(s):  
Dna Sequencing ◽  
Quality Assessment ◽  
Clinical Laboratory ◽  
External Quality Assessment ◽  
Sequence Data ◽  
False Negative ◽  
Read Length ◽  
External Quality ◽  
External Quality Assessment Scheme

Abstract Background: In the past 15 years, clinical laboratory science has been transformed by the use of technologies that cross the traditional boundaries between laboratory disciplines. However, during this period, issues of quality have not always been given adequate attention. The European Molecular Genetics Quality Network (EMQN) has developed a novel external quality assessment scheme for evaluation of DNA sequencing. We report the results of an international survey of the quality of DNA sequencing among 64 laboratories from 21 countries. Methods: Current practice for DNA sequence analysis was established by use of an online questionnaire. Participating laboratories were provided with 4 DNA samples of validated genotype. Evaluation of the results included assessing the quality of sequence data, variant genotypes, and mutation nomenclature. To accommodate variations in mutation nomenclature, variants indicated by participants were scored for compliance with 3 acceptable marking schemes. Results: A total of 346 genotypes were analyzed. Of these, 19 (5%) genotyping errors were made. Of these, 10 (53%) were false-negative and 9 (47%) were false-positive results. A further 27 (8%) errors were made in naming mutations. Results were analyzed for 3 indicators of data quality: PHRED quality scores, Quality Read Length, and Quality Read Overlap. Most laboratories produced results of acceptable diagnostic quality as judged by these indicators. The results were used to calculate a consensus benchmark for DNA sequencing against which individual laboratories could rank their performance. Conclusions: We propose that the consensus benchmark can be used as a baseline against which the aggregate and individual laboratory standard of DNA sequencing may be tracked from year to year.

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