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Ruiz-Tagle C, García P, Hernández M, Balcells ME. Evaluation of concordance of new QuantiFERON-TB Gold Plus platforms for Mycobacterium tuberculosis infection diagnosis in a prospective cohort of household contacts. Microbiol Spectr 2024:e0046924. [PMID: 38975791 DOI: 10.1128/spectrum.00469-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Accepted: 05/28/2024] [Indexed: 07/09/2024] Open
Abstract
Interferon-gamma (IFN-γ) release assays play a pivotal role in tuberculosis infection (TBI) diagnosis, with QuantiFERON-TB Gold Plus-an enzyme-linked immunosorbent assay (ELISA)-among the most widely utilized. Newer QuantiFERON-TB platforms with shorter turnaround times were recently released. We aimed to evaluate these platforms' agreement in the diagnosis of TBI. Blood samples from a prospective cohort of tuberculosis household contacts were collected at baseline and after 12 weeks of follow-up, and tested with LIAISON, an automated chemiluminescence immunoassay (CLIA) system, QIAreach, a lateral flow (QFT-LF) semi-automated immunoassay, and the ELISA QuantiFERON-TB Gold Plus platform. Test concordances were analyzed. ELISA vs CLIA overall agreement was 83.3% for all tested samples (120/144) [Cohen's kappa coefficient (κ): 0.66 (95% CI: 0.54-0.77)]. Samples positive with CLIA provided consistently higher IFN-γ levels than with ELISA (P < 0.001). Twenty-four (16.7%) discordant pairs were obtained, all CLIA-positive/ELISA-negative: 15 (62.5%) had CLIA IFN-γ levels within borderline values (0.35-0.99 IU/mL) and 9 (37.5%) >0.99 IU/mL. QFT-LF showed only 76.4% (68/89) overall agreement with ELISA [κ: 0.53 (95% CI: 0.37-0.68)] with 21 (23.6%) discordant results obtained, all QFT-LF-positive/ELISA-negative. Overall concordance between ELISA and CLIA platforms was substantial, and only moderate between ELISA and QFT-LF. The CLIA platform yielded higher IFN-γ levels than ELISA, leading to an almost 17% higher positivity rate. The techniques do not seem interchangeable, and validation against other gold standards, such as microbiologically-confirmed tuberculosis disease, is required to determine whether these cases represent true new infections or whether CLIA necessitates a higher cutoff. IMPORTANCE Tuberculosis is an airborne infectious disease caused by Mycobacterium tuberculosis that affects over 10 million people annually, with over 2 billion people carrying an asymptomatic tuberculosis infection (TBI) worldwide. Currently, TBI diagnosis includes tuberculin skin test and the blood-based interferon-gamma (IFN-γ) release assays, with Qiagen QuantiFERON-TB Gold Plus (QFT) being among those most widely utilized. We evaluated Qiagen's newer QFT platforms commercially available in a prospective cohort of tuberculosis contacts. A substantial agreement was obtained between the current QFT-enzyme-linked immunosorbent assay (ELISA) and the new QFT-chemiluminescence immunoassay (CLIA) platform, although QFT-CLIA provided higher concentrations of IFN-γ, leading to a 16.6% higher positivity rate. We highlight that both platforms may not be directly interchangeable and that further validation is required.
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Affiliation(s)
- Cinthya Ruiz-Tagle
- Departamento de Enfermedades Infecciosas del Adulto, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Patricia García
- Departamento de Laboratorios Clínicos, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Mariluz Hernández
- Equipo Técnico de Tuberculosis, Dirección de Servicio de Salud Oriente, Santiago, Chile
| | - María Elvira Balcells
- Departamento de Enfermedades Infecciosas del Adulto, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
- Red de Salud UC-CHRISTUS, Santiago, Chile
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Fernández-Moreno R, Páez-Vega A, Rodríguez-Cano D, Salinas A, Rodríguez-Cantalejo F, Jurado A, Torre-Cisneros J, Cantisán S. QuantiFERON-CMV assay by chemiluminescence immunoassay: Is it more suitable for real-live monitoring of transplant patients? J Clin Virol 2024; 171:105651. [PMID: 38346360 DOI: 10.1016/j.jcv.2024.105651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 01/30/2024] [Accepted: 02/07/2024] [Indexed: 03/17/2024]
Abstract
BACKGROUND The QuantiFERONCMV (QF-CMV) assay is an interferon-gamma release assay (IGRA) used to monitor CMV-specific cell-mediated immunity (CMV-CMI) by ELISA in transplant patients. However, a chemiluminescent immunoassay (CLIA) has been developed to quantify IFNG in the QuantiFERON-Tuberculosis (TB) to detect latent TB infection. OBJECTIVES The aim of this work is to compare the results of QF-CMV by ELISA with those obtained by CLIA in an automated Liaison XL analyzer using the QuantiFERON-TB Gold Plus reagents. STUDY DESIGN The QF-CMV assay had been performed by ELISA in kidney and lung transplant patients between July 2019-April 2023 at the IMIBIC/Reina Sofía Hospital (Cordoba, Spain). The remaining QF-CMV supernatants had been preserved at -80 ºC from then. Now, the IFNG levels in the same samples were determined by CLIA. RESULTS One hundred and three QF-CMV supernatants from kidney (n = 50) and lung (n = 53) transplant patients were selected. An agreement of 87.4 % (kappa coefficient 0.788) between CLIA and ELISA was observed. Thirteen (12.6 %) discrepant results were detected. Some Indeterminate results by ELISA converted to Non-reactive by CLIA (0.53-0.92 IU/mL for Mitogen-Nil values). Likewise, borderline Non-reactive results by ELISA were above the 0.2 IU/mL cut-off by CLIA and then were Reactive (0.21-0.31 for CMV-Nil values). CONCLUSION CLIA shows substantial concordance with ELISA and acceptable discrepancies. The possible higher sensitivity of CLIA returns a higher number of Reactive results, which entails potential clinical consequences. Therefore, a new threshold to confer protection against CMV infection after transplantation needs to be defined.
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Affiliation(s)
- Raquel Fernández-Moreno
- Spanish Network for Research in Infectious Diseases (REIPI), Centro de Investigación Biomédica en Red de Enfermedades Infecciosas (CIBERINFEC), Instituto de Salud Carlos III, Madrid, Spain; Maimonides Biomedical Research Institute of Cordoba (IMIBIC)/Reina Sofía University Hospital/University of Cordoba, Cordoba, Spain
| | - Aurora Páez-Vega
- Spanish Network for Research in Infectious Diseases (REIPI), Centro de Investigación Biomédica en Red de Enfermedades Infecciosas (CIBERINFEC), Instituto de Salud Carlos III, Madrid, Spain; Maimonides Biomedical Research Institute of Cordoba (IMIBIC)/Reina Sofía University Hospital/University of Cordoba, Cordoba, Spain
| | | | - Ana Salinas
- Spanish Network for Research in Infectious Diseases (REIPI), Centro de Investigación Biomédica en Red de Enfermedades Infecciosas (CIBERINFEC), Instituto de Salud Carlos III, Madrid, Spain; Maimonides Biomedical Research Institute of Cordoba (IMIBIC)/Reina Sofía University Hospital/University of Cordoba, Cordoba, Spain
| | | | - Aurora Jurado
- Immunology Department, Reina Sofía University Hospital, Cordoba, Spain
| | - Julián Torre-Cisneros
- Spanish Network for Research in Infectious Diseases (REIPI), Centro de Investigación Biomédica en Red de Enfermedades Infecciosas (CIBERINFEC), Instituto de Salud Carlos III, Madrid, Spain; Maimonides Biomedical Research Institute of Cordoba (IMIBIC)/Reina Sofía University Hospital/University of Cordoba, Cordoba, Spain; Infectious Diseases Unit, Reina Sofía University Hospital, Cordoba, Spain.
| | - Sara Cantisán
- Spanish Network for Research in Infectious Diseases (REIPI), Centro de Investigación Biomédica en Red de Enfermedades Infecciosas (CIBERINFEC), Instituto de Salud Carlos III, Madrid, Spain; Maimonides Biomedical Research Institute of Cordoba (IMIBIC)/Reina Sofía University Hospital/University of Cordoba, Cordoba, Spain; Immunology Department, Reina Sofía University Hospital, Cordoba, Spain; Infectious Diseases Unit, Reina Sofía University Hospital, Cordoba, Spain
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Masiá M, de la Rica A, Fernández-González M, García JA, Padilla S, García-Abellán J, Botella Á, Mascarell P, Gutiérrez F. Integrating SARS-CoV-2-specific interferon-γ release assay testing in the evaluation of patients hospitalized with COVID-19. Microbiol Spectr 2023; 11:e0241923. [PMID: 37855635 PMCID: PMC10715100 DOI: 10.1128/spectrum.02419-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 09/06/2023] [Indexed: 10/20/2023] Open
Abstract
IMPORTANCE The cellular immune response is essential in the protection against severe disease in patients with established SARS-CoV-2 infection. The novelty of this study lies in the evaluation of the overall performance of a standardized assay to measure cellular immune response, the SARS-CoV-2-specific interferon-γ release assay (IGRA), in hospitalized patients with severe COVID-19. The SARS-CoV-2 IGRA was shown to accurately classify patients based on disease severity and prognosis, and the study revealed that test performance was not affected by the SARS-CoV-2 variant or control tube results. We identified an assay cut-off point with a high negative predictive value against mortality. The SARS-CoV-2 IGRA in patients hospitalized for COVID-19 may be a useful tool to assess cellular immunity and adopt targeted therapeutic and preventive measures.
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Affiliation(s)
- Mar Masiá
- Infectious Diseases Unit, Hospital General Universitario de Elche, Alicant, Spain
- CIBER de Enfermedades Infecciosas, Instituto de Salud Carlos III, Madrid, Spain
- Clinical Medicine Department, Universidad Miguel Hernández, San Juan de Alicante, Spain
| | - Alba de la Rica
- Infectious Diseases Unit, Hospital General Universitario de Elche, Alicant, Spain
- Microbiology Service, Hospital General Universitario de Elche, Alicant, Spain
| | - Marta Fernández-González
- Infectious Diseases Unit, Hospital General Universitario de Elche, Alicant, Spain
- CIBER de Enfermedades Infecciosas, Instituto de Salud Carlos III, Madrid, Spain
| | - José Alberto García
- Infectious Diseases Unit, Hospital General Universitario de Elche, Alicant, Spain
- CIBER de Enfermedades Infecciosas, Instituto de Salud Carlos III, Madrid, Spain
| | - Sergio Padilla
- Infectious Diseases Unit, Hospital General Universitario de Elche, Alicant, Spain
- CIBER de Enfermedades Infecciosas, Instituto de Salud Carlos III, Madrid, Spain
- Clinical Medicine Department, Universidad Miguel Hernández, San Juan de Alicante, Spain
| | - Javier García-Abellán
- Infectious Diseases Unit, Hospital General Universitario de Elche, Alicant, Spain
- CIBER de Enfermedades Infecciosas, Instituto de Salud Carlos III, Madrid, Spain
- Clinical Medicine Department, Universidad Miguel Hernández, San Juan de Alicante, Spain
| | - Ángela Botella
- Infectious Diseases Unit, Hospital General Universitario de Elche, Alicant, Spain
| | - Paula Mascarell
- Infectious Diseases Unit, Hospital General Universitario de Elche, Alicant, Spain
| | - Félix Gutiérrez
- Infectious Diseases Unit, Hospital General Universitario de Elche, Alicant, Spain
- CIBER de Enfermedades Infecciosas, Instituto de Salud Carlos III, Madrid, Spain
- Clinical Medicine Department, Universidad Miguel Hernández, San Juan de Alicante, Spain
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Mafi S, Alain S, Hantz S. Evaluation of the fully automated LIAISON®XL chemiluminescence analyzer for QuantiFERON®-CMV testing in transplant recipients. J Clin Virol 2023; 166:105550. [PMID: 37527584 DOI: 10.1016/j.jcv.2023.105550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 07/17/2023] [Accepted: 07/19/2023] [Indexed: 08/03/2023]
Abstract
BACKGROUND Monitoring CMV-specific cell-mediated immunity by the QuantiFERON®-CMV (QF-CMV) may be useful in predicting the risk of CMV infection in transplant recipients (TR). OBJECTIVES As the QuantiFERON-Tuberculosis (QFT®-Plus) became available on the fully automated LIAISON®XL chemiluminescence (CLIA) analyzer, we evaluated the performance of the QF-CMV on the LIAISON®XL analyzer using the QuantiFERON®-TB Gold Plus reagent. STUDY DESIGN Between 2018 and 2022, 81 samples from TR were collected at the Department of Virology of Limoges Hospital, France. Whole blood was collected into each of the three QF-CMV collection tubes: a CMV-antigen tube (QF-Ag), a mitogen tube (QF-Mg) (positive control), and a nil tube (negative control). The QF-CMV was performed on the LIAISON®XL analyzer, and results were compared with those obtained by conventional microplate ELISA. RESULTS Intra- and inter-assay coefficients of variation were inferior to 20%. No inter-sample contamination was found (p=0.366). The level of concordance between CLIA and the commonly used ELISA method was 88.9%. Positive and negative percent agreements were 92.3% and 85.7%, respectively, with a very good agreement between assays (κ=0.818). Most discordances were due to indeterminate- or negative-ELISA/positive-CLIA results (most of ELISA results were borderline). Linear regression analyses demonstrated a strong correlation between both assays (QF-Ag Pearson's r=0.978, QF-Mg Pearson's r=0.963). No significant difference was observed in median QF-CMV values between both assays (QF-Ag p=0.776; QF-Mg p=0.853; Mann-Whitney U test). The Bland-Altman plots showed a minor difference in IFN-γ release (QF-Ag -0.069 IU/ml, 95% limits of agreement (LoA): -1.589; 1.451; QF-Mg 0.190 IU/ml, 95% LoA: -2.070; 2.450). CONCLUSION Automated QF-CMV with CLIA is comparable to QF-CMV performed by ELISA with a presumably higher sensitivity for IFN-γ detection that may result in the conversion of samples close to the ELISA cut-off into positive results. Moreover, the use of a random-access analyzer allows to optimize the follow-up of TR.
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Affiliation(s)
- Sarah Mafi
- French National Reference Center for Herpesviruses, Bacteriology, Virology, Hygiene Department, CHU Limoges, F-87000 Limoges, France; INSERM, RESINFIT, U1092, F-87000, Limoges, France.
| | - Sophie Alain
- French National Reference Center for Herpesviruses, Bacteriology, Virology, Hygiene Department, CHU Limoges, F-87000 Limoges, France; INSERM, RESINFIT, U1092, F-87000, Limoges, France
| | - Sébastien Hantz
- French National Reference Center for Herpesviruses, Bacteriology, Virology, Hygiene Department, CHU Limoges, F-87000 Limoges, France; INSERM, RESINFIT, U1092, F-87000, Limoges, France.
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Buron V, Banaei N. Inflated Gamma Interferon Response with QuantiFERON-TB Gold Plus Using the Automated Liaison XL Analyzer: a Testing Algorithm To Mitigate False-Positive Results in Low-Incidence Settings. J Clin Microbiol 2023; 61:e0029523. [PMID: 37195172 PMCID: PMC10281139 DOI: 10.1128/jcm.00295-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 04/10/2023] [Indexed: 05/18/2023] Open
Abstract
The Liaison XL chemiluminescence immunoassay (CLIA) analyzer allows total automation of gamma interferon (IFN-γ) measurement for the QuantiFERON-TB Gold Plus assay (QFT-Plus) that is used to diagnose Mycobacterium tuberculosis infection. To evaluate CLIA accuracy, plasma samples from 278 patients undergoing QFT-Plus testing were first tested with an enzyme-linked immunosorbent assay (ELISA; 150 negatives and 128 positives) and subsequently with the CLIA. Three strategies to mitigate false-positive CLIA results were investigated in 220 samples with borderline-negative ELISA results (TB1 and/or TB2, 0.1 to 0.34 IU/mL). The Bland-Altman plot of difference versus average of the two IFN-γ measurements in the Nil and antigen (TB1 and TB2) tubes showed higher IFN-γ measurements across the range of values with the CLIA than with the ELISA. Bias was 0.21 IU/mL (standard deviation, 0.61; 95% confidence interval [CI], -1.0 to 1.41). Linear regression of difference versus average had a slope of 0.08 (95% CI, 0.05 to 0.10), which was significantly nonzero (P < 0.0001). The CLIA had positive and negative percent agreement levels with the ELISA of 91.7% (121/132) and 95.2% (139/146), respectively. In borderline-negative samples tested with ELISA, CLIA was positive in 42.7% (94/220). CLIA with a standard curve resulted in 36.4% (80/220) positivity. Retesting CLIA false positives (TB1 or TB2 range, 0 to ≤1.3 IU/mL) with ELISA reduced false positives by 84.3% (59/70). Retesting with CLIA reduced the false-positive rate by 10.4% (8/77). Implementing the Liaison CLIA for QFT-Plus in low-incidence settings risks falsely elevating conversion rates and overburdening clinics and overtreating patients. Confirming borderline positives with ELISA is a viable strategy to mitigate false-positive CLIA results.
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Affiliation(s)
- Vladimir Buron
- Clinical Microbiology Laboratory, Stanford Health Care, Stanford, California, USA
| | - Niaz Banaei
- Clinical Microbiology Laboratory, Stanford Health Care, Stanford, California, USA
- Department of Pathology, Stanford University School of Medicine, Stanford, California, USA
- Division of Infectious Diseases & Geographic Medicine, Stanford University School of Medicine, Stanford, California, USA
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Ortiz-Brizuela E, Apriani L, Mukherjee T, Lachapelle-Chisholm S, Miedy M, Lan Z, Korobitsyn A, Ismail N, Menzies D. Assessing the Diagnostic Performance of New Commercial Interferon-γ Release Assays for Mycobacterium tuberculosis Infection: A Systematic Review and Meta-Analysis. Clin Infect Dis 2023; 76:1989-1999. [PMID: 36688489 PMCID: PMC10249994 DOI: 10.1093/cid/ciad030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 01/05/2023] [Accepted: 01/13/2023] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND We compared 6 new interferon-γ release assays (IGRAs; hereafter index tests: QFT-Plus, QFT-Plus CLIA, QIAreach, Wantai TB-IGRA, Standard E TB-Feron, and T-SPOT.TB/T-Cell Select) with World Health Organization (WHO)-endorsed tests for tuberculosis infection (hereafter reference tests). METHODS Data sources (1 January 2007-18 August 2021) were Medline, Embase, Web of Science, Cochrane Database of Systematic Reviews, and manufacturers' data. Cross-sectional and cohort studies comparing the diagnostic performance of index and reference tests were selected. The primary outcomes of interest were the pooled differences in sensitivity and specificity between index and reference tests. The certainty of evidence (CoE) was summarized using the GRADE approach. RESULTS Eighty-seven studies were included (44 evaluated the QFT-Plus, 4 QFT-Plus CLIA, 3 QIAreach, 26 TB-IGRA, 10 TB-Feron [1 assessing the QFT-Plus], and 1 T-SPOT.TB/T-Cell Select). Compared to the QFT-GIT, QFT Plus's sensitivity was 0.1 percentage points lower (95% confidence interval [CI], -2.8 to 2.6; CoE: moderate), and its specificity 0.9 percentage points lower (95% CI, -1.0 to -.9; CoE: moderate). Compared to QFT-GIT, TB-IGRA's sensitivity was 3.0 percentage points higher (95% CI, -.2 to 6.2; CoE: very low), and its specificity 2.6 percentage points lower (95% CI, -4.2 to -1.0; CoE: low). Agreement between the QFT-Plus CLIA and QIAreach with QFT-Plus was excellent (pooled κ statistics of 0.86 [95% CI, .78 to .94; CoE: low]; and 0.96 [95% CI, .92 to 1.00; CoE: low], respectively). The pooled κ statistic comparing the TB-Feron and the QFT-Plus or QFT-GIT was 0.85 (95% CI, .79 to .92; CoE: low). CONCLUSIONS The QFT-Plus and the TB-IGRA have very similar sensitivity and specificity as WHO-approved IGRAs.
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Affiliation(s)
- Edgar Ortiz-Brizuela
- McGill International Tuberculosis Centre, Department of Medicine, McGill University, Montreal, Quebec, Canada
- Department of Medicine, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Lika Apriani
- Tuberculosis Working Group, Research Centre for Care and Control of Infectious Diseases, Universitas Padjadjaran, Bandung, Indonesia
- Department of Public Health, Faculty of Medicine, Universitas Padjadjaran, Bandung, Indonesia
| | - Tania Mukherjee
- Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia
| | - Sophie Lachapelle-Chisholm
- McGill International Tuberculosis Centre, Department of Medicine, McGill University, Montreal, Quebec, Canada
| | - Michele Miedy
- McGill University Health Center, Department of Intensive Care Unit, McGill University, Montreal, Quebec, Canada
| | - Zhiyi Lan
- McGill International Tuberculosis Centre, Department of Medicine, McGill University, Montreal, Quebec, Canada
| | - Alexei Korobitsyn
- Global Tuberculosis Programme, World Health Organization, Geneva, Switzerland
| | - Nazir Ismail
- Global Tuberculosis Programme, World Health Organization, Geneva, Switzerland
| | - Dick Menzies
- McGill International Tuberculosis Centre, Department of Medicine, McGill University, Montreal, Quebec, Canada
- Respiratory Epidemiology and Clinical Research Unit, Research Institute of the McGill University Health Centre, Montreal Chest Institute, McGill University, Montreal, Quebec, Canada
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Repeatability of QuantiFERON-TB gold plus testing utilizing microparticle chemiluminescence. J Immunol Methods 2022; 509:113340. [PMID: 36030829 DOI: 10.1016/j.jim.2022.113340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 08/11/2022] [Accepted: 08/18/2022] [Indexed: 11/20/2022]
Abstract
BACKGROUND Detection of latent Mycobacterium tuberculosis (LTBI) in patients is important to prevent active infection and the spread of disease, particularly in vulnerable patient populations. In 2020, a kit on the high throughput Liaison XL (DiaSorin) became commercially available for the analysis of QuantiFERON-TB Gold Plus assay (Qiagen). Pilot testing indicated suboptimal repeatability of some samples with this assay. This study provides an extensive assessment of repeatability with DiaSorin system. RESULTS Repeat testing of 481 IGRA positive samples, demonstrated substantial variability upon repeat analysis. Repeat results for TB1 and TB2 tubes, showed 73.73% and 72.82% concordance with initial results, respectively. TB1 and TB2 tube values minus the nil (IU/mL) were significantly higher in samples that were repeat positive (p < 0.001). Repeat results had better concordance with initial results if both TB1 and TB2 tubes were positive. Samples with TB1 tube values minus the nil (IU/mL) ≥ 4.54 and TB2 tube values minus the nil (IU/mL) ≥ 4.78 were found to always repeat positive. Assigning a threshold of 1.55 IU/mL for the TB1 tube value minus the nil and 1.45 IU/mL for the TB2 tube value minus the nil yielded a positive predictive value ≥95%. CONCLUSION These results identified a potential role for retesting of select IGRA positive samples on the Diasorin Liaison XL platform due to the high proportion of samples that show a lack of repeatability. Additionally, we identified a threshold that would determine samples most likely to repeat test positive and which samples should be retested.
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Evaluation of the Fully Automated Chemiluminescence Analyzer Liaison XL for the Performance of the QuantiFERON-TB Gold Plus Assay in an Area with a Low Incidence of Tuberculosis. J Clin Microbiol 2021; 59:e0060321. [PMID: 34076474 DOI: 10.1128/jcm.00603-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Diagnosis of latent tuberculosis infection (LTBI) is considered key in the control of tuberculosis. Interferon gamma (IFN-γ) release assays, such as the QuantiFERON-TB Gold Plus test (QFT-Plus), are now widely implemented for the in vitro diagnosis of LTBI. To date, the detection and quantification of IFN-γ has been mostly performed with semiautomated enzyme-linked immunosorbent assays (ELISAs), but several limitations currently exist. The study aims to evaluate the chemiluminescence immunoassay (CLIA) analyzer Liaison XL compared to ELISA for the performance of the QFT-Plus test. Between February and April 2020, 333 heparin blood samples from 323 adult patients were collected at a tertiary teaching hospital in Barcelona, Spain. Overall, the CLIA analyzer Liaison XL performed well for the detection of IFN-γ compared to the ELISA method, demonstrating substantial agreement (κ, 0.872) and great correlation between assays (r, >0.950). CLIA produced significantly higher values of IFN-γ IU per milliliter than the ELISA (P = 0.004 for the TB1 tube and P = 0.010 for the TB2 tube). Many discrepant cases (8/15, 53.3%) corresponded to indeterminate results with ELISA (NIL-corrected mitogen value of <0.5 IU/ml), which, when analyzed with the CLIA analyzer Liaison XL, reverted to interpretable results. In conclusion, this analysis suggests that CLIA presents a greater sensitivity for the identification of LTBI, especially among immunocompromised patients. Furthermore, the analytical variability reported between both ELISA and CLIA methods, especially around the standardized 0.35-IU/ml positivity threshold, suggests the need to refine the interpretative algorithm.
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