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Zaporojan N, Negrean RA, Hodișan R, Zaporojan C, Csep A, Zaha DC. Evolution of Laboratory Diagnosis of Tuberculosis. Clin Pract 2024; 14:388-416. [PMID: 38525709 PMCID: PMC10961697 DOI: 10.3390/clinpract14020030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 02/15/2024] [Accepted: 02/19/2024] [Indexed: 03/26/2024] Open
Abstract
Tuberculosis (TB) is an infectious disease of global public health importance caused by the Mycobacterium tuberculosis complex. Despite advances in diagnosis and treatment, this disease has worsened with the emergence of multidrug-resistant strains of tuberculosis. We aim to present and review the history, progress, and future directions in the diagnosis of tuberculosis by evaluating the current methods of laboratory diagnosis of tuberculosis, with a special emphasis on microscopic examination and cultivation on solid and liquid media, as well as an approach to molecular assays. The microscopic method, although widely used, has its limitations, and the use and evaluation of other techniques are essential for a complete and accurate diagnosis. Bacterial cultures, both in solid and liquid media, are essential methods in the diagnosis of TB. Culture on a solid medium provides specificity and accuracy, while culture on a liquid medium brings rapidity and increased sensitivity. Molecular tests such as LPA and Xpert MTB/RIF have been found to offer significant benefits in the rapid and accurate diagnosis of TB, including drug-resistant forms. These tests allow the identification of resistance mutations and provide essential information for choosing the right treatment. We conclude that combined diagnostic methods, using several techniques and approaches, provide the best result in the laboratory diagnosis of TB. Improving the quality and accessibility of tests, as well as the implementation of advanced technologies, is essential to help improve the sensitivity, efficiency, and accuracy of TB diagnosis.
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Affiliation(s)
- Natalia Zaporojan
- Doctoral School of Biomedical Sciences, University of Oradea, Str. Universitatii 1, 410087 Oradea, Romania; (N.Z.)
| | - Rodica Anamaria Negrean
- Department of Preclinical Disciplines, Faculty of Medicine and Pharmacy, University of Oradea, P-ta 1 December 10, 410087 Oradea, Romania
| | - Ramona Hodișan
- Doctoral School of Biomedical Sciences, University of Oradea, Str. Universitatii 1, 410087 Oradea, Romania; (N.Z.)
- Department of Preclinical Disciplines, Faculty of Medicine and Pharmacy, University of Oradea, P-ta 1 December 10, 410087 Oradea, Romania
| | - Claudiu Zaporojan
- Emergency County Hospital Bihor, Str. Republicii 37, 410167 Oradea, Romania
| | - Andrei Csep
- Department of Psycho-Neurosciences and Recovery, Faculty of Medicine and Pharmacy, University of Oradea, P-ta 1 December 10, 410087 Oradea, Romania
| | - Dana Carmen Zaha
- Doctoral School of Biomedical Sciences, University of Oradea, Str. Universitatii 1, 410087 Oradea, Romania; (N.Z.)
- Department of Preclinical Disciplines, Faculty of Medicine and Pharmacy, University of Oradea, P-ta 1 December 10, 410087 Oradea, Romania
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2
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Brito GMXD, Mafort TT, Ribeiro-Alves M, Reis LVTD, Leung J, Leão RS, Rufino R, Rodrigues LS. Diagnostic performance of the Xpert MTB/RIF assay in BAL fluid samples from patients under clinical suspicion of pulmonary tuberculosis: a tertiary care experience in a high-tuberculosis-burden area. ACTA ACUST UNITED AC 2021; 47:e20200581. [PMID: 34008762 PMCID: PMC8332835 DOI: 10.36416/1806-3756/e20200581] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Accepted: 03/08/2021] [Indexed: 11/17/2022]
Abstract
OBJECTIVE To assess the diagnostic performance of the Xpert MTB/RIF assay, a rapid molecular test for tuberculosis, comparing it with that of AFB staining and culture, in BAL fluid (BALF) samples from patients with clinically suspected pulmonary tuberculosis (PTB) who are sputum smear-negative or produce sputum samples of insufficient quantity. METHODS This was a retrospective study of 140 cases of suspected PTB in patients who were smear-negative or produced insufficient sputum samples and were evaluated at a tertiary teaching hospital in the city of Rio de Janeiro, Brazil. All of the patients underwent fiberoptic bronchoscopy with BAL. The BALF specimens were evaluated by AFB staining, mycobacterial culture, and the Xpert MTB/RIF assay. RESULTS Among the 140 patients, results for all three microbiological examinations were available for 73 (52.1%), of whom 22 tested positive on culture, 17 tested positive on AFB staining, and 20 tested positive on the Xpert MTB/RIF assay. The sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy for AFB staining were 68.1%, 96.1%, 88.2%, 87.5%, and 87.6%, respectively, compared with 81.8%, 96.1%, 90.0%, 92.4%, and 91.8%, respectively, for the Xpert MTB/RIF assay. The agreement between AFB staining and culture was 82.3% (kappa = 0.46; p < 0.0001), whereas that between the Xpert MTB/RIF assay and culture was 91.8% (kappa = 0.8; p < 0.0001). CONCLUSIONS In BALF samples, the Xpert MTB/RIF assay performs better than do traditional methods, providing a reliable alternative to sputum analysis in suspected cases of PTB. However, the rate of discordant results merits careful consideration.
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Affiliation(s)
- Guilherme Machado Xavier de Brito
- . Laboratório de Imunopatologia, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro - UERJ - Rio de Janeiro (RJ) Brasil
| | - Thiago Thomaz Mafort
- . Disciplina de Pneumologia e Tisiologia, Hospital Universitário Pedro Ernesto, Universidade do Estado do Rio de Janeiro - UERJ - Rio de Janeiro (RJ) Brasil
| | - Marcelo Ribeiro-Alves
- . Laboratório de Pesquisas Clínicas em DST/AIDS, Instituto Nacional de Infectologia Evandro Chagas, Fundação Oswaldo Cruz, Rio de Janeiro, Rio de Janeiro (RJ) Brasil
| | - Larissa Vieira Tavares Dos Reis
- . Disciplina de Pneumologia e Tisiologia, Hospital Universitário Pedro Ernesto, Universidade do Estado do Rio de Janeiro - UERJ - Rio de Janeiro (RJ) Brasil
| | - Janaína Leung
- . Disciplina de Pneumologia e Tisiologia, Hospital Universitário Pedro Ernesto, Universidade do Estado do Rio de Janeiro - UERJ - Rio de Janeiro (RJ) Brasil
| | - Robson Souza Leão
- . Departamento de Microbiologia, Imunologia e Parasitologia, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro - UERJ - Rio de Janeiro (RJ) Brasil
| | - Rogério Rufino
- . Disciplina de Pneumologia e Tisiologia, Hospital Universitário Pedro Ernesto, Universidade do Estado do Rio de Janeiro - UERJ - Rio de Janeiro (RJ) Brasil
| | - Luciana Silva Rodrigues
- . Laboratório de Imunopatologia, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro - UERJ - Rio de Janeiro (RJ) Brasil
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3
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Zifodya JS, Kreniske JS, Schiller I, Kohli M, Dendukuri N, Schumacher SG, Ochodo EA, Haraka F, Zwerling AA, Pai M, Steingart KR, Horne DJ. Xpert Ultra versus Xpert MTB/RIF for pulmonary tuberculosis and rifampicin resistance in adults with presumptive pulmonary tuberculosis. Cochrane Database Syst Rev 2021; 2:CD009593. [PMID: 33616229 DOI: 10.1002/14651858.cd009593.pub5] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Xpert MTB/RIF and Xpert MTB/RIF Ultra (Xpert Ultra) are World Health Organization (WHO)-recommended rapid tests that simultaneously detect tuberculosis and rifampicin resistance in people with signs and symptoms of tuberculosis. This review builds on our recent extensive Cochrane Review of Xpert MTB/RIF accuracy. OBJECTIVES To compare the diagnostic accuracy of Xpert Ultra and Xpert MTB/RIF for the detection of pulmonary tuberculosis and detection of rifampicin resistance in adults with presumptive pulmonary tuberculosis. For pulmonary tuberculosis and rifampicin resistance, we also investigated potential sources of heterogeneity. We also summarized the frequency of Xpert Ultra trace-positive results, and estimated the accuracy of Xpert Ultra after repeat testing in those with trace-positive results. SEARCH METHODS We searched the Cochrane Infectious Diseases Group Specialized Register, MEDLINE, Embase, Science Citation Index, Web of Science, LILACS, Scopus, the WHO ICTRP, the ISRCTN registry, and ProQuest to 28 January 2020 with no language restriction. SELECTION CRITERIA We included diagnostic accuracy studies using respiratory specimens in adults with presumptive pulmonary tuberculosis that directly compared the index tests. For pulmonary tuberculosis detection, the reference standards were culture and a composite reference standard. For rifampicin resistance, the reference standards were culture-based drug susceptibility testing and line probe assays. DATA COLLECTION AND ANALYSIS Two review authors independently extracted data using a standardized form, including data by smear and HIV status. We assessed risk of bias using QUADAS-2 and QUADAS-C. We performed meta-analyses comparing pooled sensitivities and specificities, separately for pulmonary tuberculosis detection and rifampicin resistance detection, and separately by reference standard. Most analyses used a bivariate random-effects model. For tuberculosis detection, we estimated accuracy in studies in participants who were not selected based on prior microscopy testing or history of tuberculosis. We performed subgroup analyses by smear status, HIV status, and history of tuberculosis. We summarized Xpert Ultra trace results. MAIN RESULTS We identified nine studies (3500 participants): seven had unselected participants (2834 participants). All compared Xpert Ultra and Xpert MTB/RIF for pulmonary tuberculosis detection; seven studies used a paired comparative accuracy design, and two studies used a randomized design. Five studies compared Xpert Ultra and Xpert MTB/RIF for rifampicin resistance detection; four studies used a paired design, and one study used a randomized design. Of the nine included studies, seven (78%) were mainly or exclusively in high tuberculosis burden countries. For pulmonary tuberculosis detection, most studies had low risk of bias in all domains. Pulmonary tuberculosis detection Xpert Ultra pooled sensitivity and specificity (95% credible interval) against culture were 90.9% (86.2 to 94.7) and 95.6% (93.0 to 97.4) (7 studies, 2834 participants; high-certainty evidence) versus Xpert MTB/RIF pooled sensitivity and specificity of 84.7% (78.6 to 89.9) and 98.4% (97.0 to 99.3) (7 studies, 2835 participants; high-certainty evidence). The difference in the accuracy of Xpert Ultra minus Xpert MTB/RIF was estimated at 6.3% (0.1 to 12.8) for sensitivity and -2.7% (-5.7 to -0.5) for specificity. If the point estimates for Xpert Ultra and Xpert MTB/RIF are applied to a hypothetical cohort of 1000 patients, where 10% of those presenting with symptoms have pulmonary tuberculosis, Xpert Ultra will miss 9 cases, and Xpert MTB/RIF will miss 15 cases. The number of people wrongly diagnosed with pulmonary tuberculosis would be 40 with Xpert Ultra and 14 with Xpert MTB/RIF. In smear-negative, culture-positive participants, pooled sensitivity was 77.5% (67.6 to 85.6) for Xpert Ultra versus 60.6% (48.4 to 71.7) for Xpert MTB/RIF; pooled specificity was 95.8% (92.9 to 97.7) for Xpert Ultra versus 98.8% (97.7 to 99.5) for Xpert MTB/RIF (6 studies). In people living with HIV, pooled sensitivity was 87.6% (75.4 to 94.1) for Xpert Ultra versus 74.9% (58.7 to 86.2) for Xpert MTB/RIF; pooled specificity was 92.8% (82.3 to 97.0) for Xpert Ultra versus 99.7% (98.6 to 100.0) for Xpert MTB/RIF (3 studies). In participants with a history of tuberculosis, pooled sensitivity was 84.2% (72.5 to 91.7) for Xpert Ultra versus 81.8% (68.7 to 90.0) for Xpert MTB/RIF; pooled specificity was 88.2% (70.5 to 96.6) for Xpert Ultra versus 97.4% (91.7 to 99.5) for Xpert MTB/RIF (4 studies). The proportion of Ultra trace-positive results ranged from 3.0% to 30.4%. Data were insufficient to estimate the accuracy of Xpert Ultra repeat testing in individuals with initial trace-positive results. Rifampicin resistance detection Pooled sensitivity and specificity were 94.9% (88.9 to 97.9) and 99.1% (97.7 to 99.8) (5 studies, 921 participants; high-certainty evidence) for Xpert Ultra versus 95.3% (90.0 to 98.1) and 98.8% (97.2 to 99.6) (5 studies, 930 participants; high-certainty evidence) for Xpert MTB/RIF. The difference in the accuracy of Xpert Ultra minus Xpert MTB/RIF was estimated at -0.3% (-6.9 to 5.7) for sensitivity and 0.3% (-1.2 to 2.0) for specificity. If the point estimates for Xpert Ultra and Xpert MTB/RIF are applied to a hypothetical cohort of 1000 patients, where 10% of those presenting with symptoms have rifampicin resistance, Xpert Ultra will miss 5 cases, and Xpert MTB/RIF will miss 5 cases. The number of people wrongly diagnosed with rifampicin resistance would be 8 with Xpert Ultra and 11 with Xpert MTB/RIF. We identified a higher number of rifampicin resistance indeterminate results with Xpert Ultra, pooled proportion 7.6% (2.4 to 21.0) compared to Xpert MTB/RIF pooled proportion 0.8% (0.2 to 2.4). The estimated difference in the pooled proportion of indeterminate rifampicin resistance results for Xpert Ultra versus Xpert MTB/RIF was 6.7% (1.4 to 20.1). AUTHORS' CONCLUSIONS Xpert Ultra has higher sensitivity and lower specificity than Xpert MTB/RIF for pulmonary tuberculosis, especially in smear-negative participants and people living with HIV. Xpert Ultra specificity was lower than that of Xpert MTB/RIF in participants with a history of tuberculosis. The sensitivity and specificity trade-off would be expected to vary by setting. For detection of rifampicin resistance, Xpert Ultra and Xpert MTB/RIF had similar sensitivity and specificity. Ultra trace-positive results were common. Xpert Ultra and Xpert MTB/RIF provide accurate results and can allow rapid initiation of treatment for rifampicin-resistant and multidrug-resistant tuberculosis.
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Affiliation(s)
- Jerry S Zifodya
- Department of Medicine, Section of Pulmonary, Critical Care, & Environmental Medicine , Tulane University, New Orleans, LA, USA
| | - Jonah S Kreniske
- Department of Internal Medicine, Tulane University School of Medicine, New Orleans, Louisiana, USA
| | - Ian Schiller
- Centre for Outcomes Research, McGill University Health Centre - Research Institute, Montreal, Canada
| | - Mikashmi Kohli
- Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, Canada
| | - Nandini Dendukuri
- Centre for Outcomes Research, McGill University Health Centre - Research Institute, Montreal, Canada
| | | | - Eleanor A Ochodo
- Centre for Evidence-based Health Care, Department of Global Health, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Frederick Haraka
- Elizabeth Glaser Pediatric AIDS Foundation, Dar es Salaam, Tanzania
- Ifakara Health Institute, Bagamoyo, Tanzania
| | - Alice A Zwerling
- School of Epidemiology & Public Health, University of Ottawa, Ottawa, Canada
| | - Madhukar Pai
- Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, Canada
| | - Karen R Steingart
- Honorary Research Fellow, Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
| | - David J Horne
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, and Firland Northwest TB Center, University of Washington, Seattle, WA, USA
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Kohli M, Schiller I, Dendukuri N, Yao M, Dheda K, Denkinger CM, Schumacher SG, Steingart KR. Xpert MTB/RIF Ultra and Xpert MTB/RIF assays for extrapulmonary tuberculosis and rifampicin resistance in adults. Cochrane Database Syst Rev 2021; 1:CD012768. [PMID: 33448348 PMCID: PMC8078545 DOI: 10.1002/14651858.cd012768.pub3] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Xpert MTB/RIF Ultra (Xpert Ultra) and Xpert MTB/RIF are World Health Organization (WHO)-recommended rapid nucleic acid amplification tests (NAATs) widely used for simultaneous detection of Mycobacterium tuberculosis complex and rifampicin resistance in sputum. To extend our previous review on extrapulmonary tuberculosis (Kohli 2018), we performed this update to inform updated WHO policy (WHO Consolidated Guidelines (Module 3) 2020). OBJECTIVES To estimate diagnostic accuracy of Xpert Ultra and Xpert MTB/RIF for extrapulmonary tuberculosis and rifampicin resistance in adults with presumptive extrapulmonary tuberculosis. SEARCH METHODS Cochrane Infectious Diseases Group Specialized Register, MEDLINE, Embase, Science Citation Index, Web of Science, Latin American Caribbean Health Sciences Literature, Scopus, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform, the International Standard Randomized Controlled Trial Number Registry, and ProQuest, 2 August 2019 and 28 January 2020 (Xpert Ultra studies), without language restriction. SELECTION CRITERIA Cross-sectional and cohort studies using non-respiratory specimens. Forms of extrapulmonary tuberculosis: tuberculous meningitis and pleural, lymph node, bone or joint, genitourinary, peritoneal, pericardial, disseminated tuberculosis. Reference standards were culture and a study-defined composite reference standard (tuberculosis detection); phenotypic drug susceptibility testing and line probe assays (rifampicin resistance detection). DATA COLLECTION AND ANALYSIS Two review authors independently extracted data and assessed risk of bias and applicability using QUADAS-2. For tuberculosis detection, we performed separate analyses by specimen type and reference standard using the bivariate model to estimate pooled sensitivity and specificity with 95% credible intervals (CrIs). We applied a latent class meta-analysis model to three forms of extrapulmonary tuberculosis. We assessed certainty of evidence using GRADE. MAIN RESULTS 69 studies: 67 evaluated Xpert MTB/RIF and 11 evaluated Xpert Ultra, of which nine evaluated both tests. Most studies were conducted in China, India, South Africa, and Uganda. Overall, risk of bias was low for patient selection, index test, and flow and timing domains, and low (49%) or unclear (43%) for the reference standard domain. Applicability for the patient selection domain was unclear for most studies because we were unsure of the clinical settings. Cerebrospinal fluid Xpert Ultra (6 studies) Xpert Ultra pooled sensitivity and specificity (95% CrI) against culture were 89.4% (79.1 to 95.6) (89 participants; low-certainty evidence) and 91.2% (83.2 to 95.7) (386 participants; moderate-certainty evidence). Of 1000 people where 100 have tuberculous meningitis, 168 would be Xpert Ultra-positive: of these, 79 (47%) would not have tuberculosis (false-positives) and 832 would be Xpert Ultra-negative: of these, 11 (1%) would have tuberculosis (false-negatives). Xpert MTB/RIF (30 studies) Xpert MTB/RIF pooled sensitivity and specificity against culture were 71.1% (62.8 to 79.1) (571 participants; moderate-certainty evidence) and 96.9% (95.4 to 98.0) (2824 participants; high-certainty evidence). Of 1000 people where 100 have tuberculous meningitis, 99 would be Xpert MTB/RIF-positive: of these, 28 (28%) would not have tuberculosis; and 901 would be Xpert MTB/RIF-negative: of these, 29 (3%) would have tuberculosis. Pleural fluid Xpert Ultra (4 studies) Xpert Ultra pooled sensitivity and specificity against culture were 75.0% (58.0 to 86.4) (158 participants; very low-certainty evidence) and 87.0% (63.1 to 97.9) (240 participants; very low-certainty evidence). Of 1000 people where 100 have pleural tuberculosis, 192 would be Xpert Ultra-positive: of these, 117 (61%) would not have tuberculosis; and 808 would be Xpert Ultra-negative: of these, 25 (3%) would have tuberculosis. Xpert MTB/RIF (25 studies) Xpert MTB/RIF pooled sensitivity and specificity against culture were 49.5% (39.8 to 59.9) (644 participants; low-certainty evidence) and 98.9% (97.6 to 99.7) (2421 participants; high-certainty evidence). Of 1000 people where 100 have pleural tuberculosis, 60 would be Xpert MTB/RIF-positive: of these, 10 (17%) would not have tuberculosis; and 940 would be Xpert MTB/RIF-negative: of these, 50 (5%) would have tuberculosis. Lymph node aspirate Xpert Ultra (1 study) Xpert Ultra sensitivity and specificity (95% confidence interval) against composite reference standard were 70% (51 to 85) (30 participants; very low-certainty evidence) and 100% (92 to 100) (43 participants; low-certainty evidence). Of 1000 people where 100 have lymph node tuberculosis, 70 would be Xpert Ultra-positive and 0 (0%) would not have tuberculosis; 930 would be Xpert Ultra-negative and 30 (3%) would have tuberculosis. Xpert MTB/RIF (4 studies) Xpert MTB/RIF pooled sensitivity and specificity against composite reference standard were 81.6% (61.9 to 93.3) (377 participants; low-certainty evidence) and 96.4% (91.3 to 98.6) (302 participants; low-certainty evidence). Of 1000 people where 100 have lymph node tuberculosis, 118 would be Xpert MTB/RIF-positive and 37 (31%) would not have tuberculosis; 882 would be Xpert MTB/RIF-negative and 19 (2%) would have tuberculosis. In lymph node aspirate, Xpert MTB/RIF pooled specificity against culture was 86.2% (78.0 to 92.3), lower than that against a composite reference standard. Using the latent class model, Xpert MTB/RIF pooled specificity was 99.5% (99.1 to 99.7), similar to that observed with a composite reference standard. Rifampicin resistance Xpert Ultra (4 studies) Xpert Ultra pooled sensitivity and specificity were 100.0% (95.1 to 100.0), (24 participants; low-certainty evidence) and 100.0% (99.0 to 100.0) (105 participants; moderate-certainty evidence). Of 1000 people where 100 have rifampicin resistance, 100 would be Xpert Ultra-positive (resistant): of these, zero (0%) would not have rifampicin resistance; and 900 would be Xpert Ultra-negative (susceptible): of these, zero (0%) would have rifampicin resistance. Xpert MTB/RIF (19 studies) Xpert MTB/RIF pooled sensitivity and specificity were 96.5% (91.9 to 98.8) (148 participants; high-certainty evidence) and 99.1% (98.0 to 99.7) (822 participants; high-certainty evidence). Of 1000 people where 100 have rifampicin resistance, 105 would be Xpert MTB/RIF-positive (resistant): of these, 8 (8%) would not have rifampicin resistance; and 895 would be Xpert MTB/RIF-negative (susceptible): of these, 3 (0.3%) would have rifampicin resistance. AUTHORS' CONCLUSIONS Xpert Ultra and Xpert MTB/RIF may be helpful in diagnosing extrapulmonary tuberculosis. Sensitivity varies across different extrapulmonary specimens: while for most specimens specificity is high, the tests rarely yield a positive result for people without tuberculosis. For tuberculous meningitis, Xpert Ultra had higher sensitivity and lower specificity than Xpert MTB/RIF against culture. Xpert Ultra and Xpert MTB/RIF had similar sensitivity and specificity for rifampicin resistance. Future research should acknowledge the concern associated with culture as a reference standard in paucibacillary specimens and consider ways to address this limitation.
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MESH Headings
- Adult
- Antibiotics, Antitubercular/therapeutic use
- Bias
- Drug Resistance, Bacterial
- False Negative Reactions
- False Positive Reactions
- Humans
- Mycobacterium tuberculosis/drug effects
- Mycobacterium tuberculosis/isolation & purification
- Nucleic Acid Amplification Techniques/methods
- Nucleic Acid Amplification Techniques/statistics & numerical data
- Reagent Kits, Diagnostic
- Rifampin/therapeutic use
- Sensitivity and Specificity
- Tuberculosis/cerebrospinal fluid
- Tuberculosis/diagnosis
- Tuberculosis/drug therapy
- Tuberculosis, Lymph Node/cerebrospinal fluid
- Tuberculosis, Lymph Node/diagnosis
- Tuberculosis, Lymph Node/drug therapy
- Tuberculosis, Meningeal/cerebrospinal fluid
- Tuberculosis, Meningeal/diagnosis
- Tuberculosis, Meningeal/drug therapy
- Tuberculosis, Multidrug-Resistant/cerebrospinal fluid
- Tuberculosis, Multidrug-Resistant/diagnosis
- Tuberculosis, Multidrug-Resistant/drug therapy
- Tuberculosis, Pleural/cerebrospinal fluid
- Tuberculosis, Pleural/diagnosis
- Tuberculosis, Pleural/drug therapy
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Affiliation(s)
- Mikashmi Kohli
- Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, Canada
| | - Ian Schiller
- Centre for Outcomes Research, McGill University Health Centre - Research Institute, Montreal, Canada
| | - Nandini Dendukuri
- Centre for Outcomes Research, McGill University Health Centre - Research Institute, Montreal, Canada
| | - Mandy Yao
- Centre for Outcomes Research, McGill University Health Centre - Research Institute, Montreal, Canada
| | - Keertan Dheda
- Centre for Lung Infection and Immunity Unit, Department of Medicine and UCT Lung Institute, University of Cape Town, Cape Town, South Africa
- Faculty of Infectious and Tropical Diseases, Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Claudia M Denkinger
- FIND, Geneva , Switzerland
- Division of Tropical Medicine, Centre for Infectious Diseases, University Hospital Heidelberg, Heidelberg, Germany
| | | | - Karen R Steingart
- Honorary Research Fellow, Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
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5
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Zong K, Luo C, Zhou H, Jiang Y, Li S. Xpert MTB/RIF assay for the diagnosis of rifampicin resistance in different regions: a meta-analysis. BMC Microbiol 2019; 19:177. [PMID: 31382894 PMCID: PMC6683411 DOI: 10.1186/s12866-019-1516-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 06/17/2019] [Indexed: 01/08/2023] Open
Abstract
Background To estimate the diagnostic accuracy of Xpert MTB/RIF for rifampicin resistance in different regions, a meta-analysis was carried out. Methods Several databases were searched for relevant studies up to March 3, 2019. A bivariate random-effects model was used to estimate the diagnostic accuracy. Results We identified 97 studies involving 26,037 samples for the diagnosis of rifampicin resistance. The pooled sensitivity, specificity and AUC of Xpert MTB/RIF for rifampicin resistance detection were 0.93 (95% CI 0.90–0.95), 0.98 (95% CI 0.96–0.98) and 0.99 (95% CI 0.97–0.99), respectively. For different regions, the pooled sensitivity were 0.94(95% CI 0.89–0.97) and 0.92 (95% CI 0.88–0.94), the pooled specificity were 0.98 (95% CI 0.94–1.00) and 0.98 (95% CI 0.96–0.99), and the AUC were 0.99 (95% CI 0.98–1.00) and 0.99 (95% CI 0.97–0.99) in high and middle/low income countries, respectively. The pooled sensitivity were 0.91 (95% CI 0.87–0.94) and 0.91 (95% CI 0.86–0.94), the pooled specificity were 0.98 (95% CI 0.96–0.99) and 0.98 (95% CI 0.96–0.99), and the AUC were 0.98 (95% CI 0.97–0.99) and 0.99 (95% CI 0.97–0.99) in high TB burden and middle/low prevalence countries, respectively. Conclusions The diagnostic accuracy of Xpert MTB/RIF for rifampicin resistance detection was excellent.
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Affiliation(s)
- Kaican Zong
- Department of Respiratory Medicine, The Seventh People's Hospital of Chongqing, Chongqing, People's Republic of China
| | - Chen Luo
- Department of Respiratory Medicine, The Seventh People's Hospital of Chongqing, Chongqing, People's Republic of China
| | - Hui Zhou
- Department of Respiratory Medicine, The Seventh People's Hospital of Chongqing, Chongqing, People's Republic of China
| | - Yangzhi Jiang
- Department of Respiratory Medicine, The Seventh People's Hospital of Chongqing, Chongqing, People's Republic of China
| | - Shiying Li
- Department of Infectious Disease, The Second Affiliated Hospital, Chongqing Medical University, 74# Linjiang Road, Chongqing, 400010, People's Republic of China.
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6
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Horne DJ, Kohli M, Zifodya JS, Schiller I, Dendukuri N, Tollefson D, Schumacher SG, Ochodo EA, Pai M, Steingart KR. Xpert MTB/RIF and Xpert MTB/RIF Ultra for pulmonary tuberculosis and rifampicin resistance in adults. Cochrane Database Syst Rev 2019; 6:CD009593. [PMID: 31173647 PMCID: PMC6555588 DOI: 10.1002/14651858.cd009593.pub4] [Citation(s) in RCA: 115] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
BACKGROUND Xpert MTB/RIF (Xpert MTB/RIF) and Xpert MTB/RIF Ultra (Xpert Ultra), the newest version, are the only World Health Organization (WHO)-recommended rapid tests that simultaneously detect tuberculosis and rifampicin resistance in persons with signs and symptoms of tuberculosis, at lower health system levels. A previous Cochrane Review found Xpert MTB/RIF sensitive and specific for tuberculosis (Steingart 2014). Since the previous review, new studies have been published. We performed a review update for an upcoming WHO policy review. OBJECTIVES To determine diagnostic accuracy of Xpert MTB/RIF and Xpert Ultra for tuberculosis in adults with presumptive pulmonary tuberculosis (PTB) and for rifampicin resistance in adults with presumptive rifampicin-resistant tuberculosis. SEARCH METHODS We searched the Cochrane Infectious Diseases Group Specialized Register, MEDLINE, Embase, Science Citation Index, Web of Science, Latin American Caribbean Health Sciences Literature, Scopus, the WHO International Clinical Trials Registry Platform, the International Standard Randomized Controlled Trial Number Registry, and ProQuest, to 11 October 2018, without language restriction. SELECTION CRITERIA Randomized trials, cross-sectional, and cohort studies using respiratory specimens that evaluated Xpert MTB/RIF, Xpert Ultra, or both against the reference standard, culture for tuberculosis and culture-based drug susceptibility testing or MTBDRplus for rifampicin resistance. DATA COLLECTION AND ANALYSIS Four review authors independently extracted data using a standardized form. When possible, we also extracted data by smear and HIV status. We assessed study quality using QUADAS-2 and performed meta-analyses to estimate pooled sensitivity and specificity separately for tuberculosis and rifampicin resistance. We investigated potential sources of heterogeneity. Most analyses used a bivariate random-effects model. For tuberculosis detection, we first estimated accuracy using all included studies and then only the subset of studies where participants were unselected, i.e. not selected based on prior microscopy testing. MAIN RESULTS We identified in total 95 studies (77 new studies since the previous review): 86 studies (42,091 participants) evaluated Xpert MTB/RIF for tuberculosis and 57 studies (8287 participants) for rifampicin resistance. One study compared Xpert MTB/RIF and Xpert Ultra on the same participant specimen.Tuberculosis detectionOf the total 86 studies, 45 took place in high tuberculosis burden and 50 in high TB/HIV burden countries. Most studies had low risk of bias.Xpert MTB/RIF pooled sensitivity and specificity (95% credible Interval (CrI)) were 85% (82% to 88%) and 98% (97% to 98%), (70 studies, 37,237 unselected participants; high-certainty evidence). We found similar accuracy when we included all studies.For a population of 1000 people where 100 have tuberculosis on culture, 103 would be Xpert MTB/RIF-positive and 18 (17%) would not have tuberculosis (false-positives); 897 would be Xpert MTB/RIF-negative and 15 (2%) would have tuberculosis (false-negatives).Xpert Ultra sensitivity (95% confidence interval (CI)) was 88% (85% to 91%) versus Xpert MTB/RIF 83% (79% to 86%); Xpert Ultra specificity was 96% (94% to 97%) versus Xpert MTB/RIF 98% (97% to 99%), (1 study, 1439 participants; moderate-certainty evidence).Xpert MTB/RIF pooled sensitivity was 98% (97% to 98%) in smear-positive and 67% (62% to 72%) in smear-negative, culture-positive participants, (45 studies). Xpert MTB/RIF pooled sensitivity was 88% (83% to 92%) in HIV-negative and 81% (75% to 86%) in HIV-positive participants; specificities were similar 98% (97% to 99%), (14 studies).Rifampicin resistance detectionXpert MTB/RIF pooled sensitivity and specificity (95% Crl) were 96% (94% to 97%) and 98% (98% to 99%), (48 studies, 8020 participants; high-certainty evidence).For a population of 1000 people where 100 have rifampicin-resistant tuberculosis, 114 would be positive for rifampicin-resistant tuberculosis and 18 (16%) would not have rifampicin resistance (false-positives); 886 would be would be negative for rifampicin-resistant tuberculosis and four (0.4%) would have rifampicin resistance (false-negatives).Xpert Ultra sensitivity (95% CI) was 95% (90% to 98%) versus Xpert MTB/RIF 95% (91% to 98%); Xpert Ultra specificity was 98% (97% to 99%) versus Xpert MTB/RIF 98% (96% to 99%), (1 study, 551 participants; moderate-certainty evidence). AUTHORS' CONCLUSIONS We found Xpert MTB/RIF to be sensitive and specific for diagnosing PTB and rifampicin resistance, consistent with findings reported previously. Xpert MTB/RIF was more sensitive for tuberculosis in smear-positive than smear-negative participants and HIV-negative than HIV-positive participants. Compared with Xpert MTB/RIF, Xpert Ultra had higher sensitivity and lower specificity for tuberculosis and similar sensitivity and specificity for rifampicin resistance (1 study). Xpert MTB/RIF and Xpert Ultra provide accurate results and can allow rapid initiation of treatment for multidrug-resistant tuberculosis.
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Affiliation(s)
- David J Horne
- University of WashingtonDepartment of Medicine, Division of Pulmonary and Critical Care Medicine, and Firland Northwest TB CenterSeattleUSA
| | - Mikashmi Kohli
- McGill UniversityDepartment of Epidemiology, Biostatistics and Occupational HealthMontrealCanada
| | - Jerry S Zifodya
- University of WashingtonPulmonary and Critical Care Medicine325 9th Avenue – Campus Box 359762SeattleUSA98104
| | - Ian Schiller
- McGill University Health Centre ‐ Research InstituteDivision of Clinical EpidemiologyMontrealCanada
| | - Nandini Dendukuri
- McGill University Health Centre ‐ Research InstituteDivision of Clinical EpidemiologyMontrealCanada
| | | | | | - Eleanor A Ochodo
- Stellenbosch UniversityCentre for Evidence‐based Health Care, Faculty of Medicine and Health SciencesPO Box 241Cape TownSouth Africa8000
| | - Madhukar Pai
- McGill UniversityDepartment of Epidemiology, Biostatistics and Occupational HealthMontrealCanada
| | - Karen R Steingart
- Department of Clinical Sciences, Liverpool School of Tropical MedicineHonorary Research FellowPembroke PlaceLiverpoolUK
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Perumal J, Dinish US, Bendt AK, Kazakeviciute A, Fu CY, Ong ILH, Olivo M. Identification of mycolic acid forms using surface-enhanced Raman scattering as a fast detection method for tuberculosis. Int J Nanomedicine 2018; 13:6029-6038. [PMID: 30323590 PMCID: PMC6177374 DOI: 10.2147/ijn.s171400] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Background Tuberculosis (TB) is the ninth leading cause of death worldwide and the leading cause from a single infectious agent, based on the WHO Global Tuberculosis Report in 2017. TB causes massive health care burdens in many parts of the world, specifically in the resource constrained developing world. Most deaths from TB could be prevented with cost effective early diagnosis and appropriate treatment. Purpose Conventional TB detection methods are either too slow as it takes a few weeks for diagnosis or they lack the specificity and accuracy. Thus the objective of this study was to develop a fast and efficient detection for TB using surface enhanced Raman scattering (SERS) technique. Methods SERS spectra for different forms of mycolic acids (MAs) that are both synthetic origin and actual extracts from the mycobacteria species were obtained by label-free direct detection mode. Similarly, we collected SERS spectra for γ-irradiated whole bacteria (WB). Measurements were done using silver (Ag) coated silicon nanopillar (Ag SNP) as SERS substrate. Results We report the SERS based detection of MA, which is a biomarker for mycobacteria species including Mycobacterium tuberculosis. For the first time, we also establish the SERS spectral characterization of the three major forms of MA - αMA, methoxy-MA, and keto-MA, in bacterial extracts and also in γ-irradiated WB. We validated our findings by mass spectrometry. SERS detection of these three forms of MA could be useful in differentiating pathogenic and nonpathogenic Mycobacterium spp. Conclusions We have demonstrated the direct detection of three major forms of MA - αMA, methoxy-MA, and keto-MA, in two different types of MA extracts from MTB bacteria, namely delipidated MA and undelipidated MA and finally in γ-irradiated WB. In the near future, this study could pave the way for a fast and efficient detection method for TB, which is of high clinical significance.
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Affiliation(s)
- Jayakumar Perumal
- Laboratory of Bio-optical Imaging, Singapore Bioimaging Consortium, Agency for Science, Technology, and Research (ASTAR), Singapore, ;
| | - U S Dinish
- Laboratory of Bio-optical Imaging, Singapore Bioimaging Consortium, Agency for Science, Technology, and Research (ASTAR), Singapore, ;
| | - Anne K Bendt
- Singapore Lipidomics Incubator, Life Sciences Institute, National University of Singapore, Singapore
| | - Agne Kazakeviciute
- Laboratory of Bio-optical Imaging, Singapore Bioimaging Consortium, Agency for Science, Technology, and Research (ASTAR), Singapore, ; .,Department of Statistical Science, University College London, London, UK
| | - Chit Yaw Fu
- Laboratory of Bio-optical Imaging, Singapore Bioimaging Consortium, Agency for Science, Technology, and Research (ASTAR), Singapore, ;
| | | | - Malini Olivo
- Laboratory of Bio-optical Imaging, Singapore Bioimaging Consortium, Agency for Science, Technology, and Research (ASTAR), Singapore, ;
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Kohli M, Schiller I, Dendukuri N, Dheda K, Denkinger CM, Schumacher SG, Steingart KR. Xpert ® MTB/RIF assay for extrapulmonary tuberculosis and rifampicin resistance. Cochrane Database Syst Rev 2018; 8:CD012768. [PMID: 30148542 PMCID: PMC6513199 DOI: 10.1002/14651858.cd012768.pub2] [Citation(s) in RCA: 115] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Tuberculosis (TB) is the world's leading infectious cause of death. Extrapulmonary TB accounts for 15% of TB cases, but the proportion is increasing, and over half a million people were newly diagnosed with rifampicin-resistant TB in 2016. Xpert® MTB/RIF (Xpert) is a World Health Organization (WHO)-recommended, rapid, automated, nucleic acid amplification assay that is used widely for simultaneous detection of Mycobacterium tuberculosis complex and rifampicin resistance in sputum specimens. This Cochrane Review assessed the accuracy of Xpert in extrapulmonary specimens. OBJECTIVES To determine the diagnostic accuracy of Xpert a) for extrapulmonary TB by site of disease in people presumed to have extrapulmonary TB; and b) for rifampicin resistance in people presumed to have extrapulmonary TB. SEARCH METHODS We searched the Cochrane Infectious Diseases Group Specialized Register, MEDLINE, Embase, Science Citation Index, Web of Science, Latin American Caribbean Health Sciences Literature (LILACS), Scopus, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform, the International Standard Randomized Controlled Trial Number (ISRCTN) Registry, and ProQuest up to 7 August 2017 without language restriction. SELECTION CRITERIA We included diagnostic accuracy studies of Xpert in people presumed to have extrapulmonary TB. We included TB meningitis and pleural, lymph node, bone or joint, genitourinary, peritoneal, pericardial, and disseminated TB. We used culture as the reference standard. For pleural TB, we also included a composite reference standard, which defined a positive result as the presence of granulomatous inflammation or a positive culture result. For rifampicin resistance, we used culture-based drug susceptibility testing or MTBDRplus as the reference standard. DATA COLLECTION AND ANALYSIS Two review authors independently extracted data, assessed risk of bias and applicability using the QUADAS-2 tool. We determined pooled predicted sensitivity and specificity for TB, grouped by type of extrapulmonary specimen, and for rifampicin resistance. For TB detection, we used a bivariate random-effects model. Recognizing that use of culture may lead to misclassification of cases of extrapulmonary TB as 'not TB' owing to the paucibacillary nature of the disease, we adjusted accuracy estimates by applying a latent class meta-analysis model. For rifampicin resistance detection, we performed univariate meta-analyses for sensitivity and specificity separately to include studies in which no rifampicin resistance was detected. We used theoretical populations with an assumed prevalence to provide illustrative numbers of patients with false positive and false negative results. MAIN RESULTS We included 66 unique studies that evaluated 16,213 specimens for detection of extrapulmonary TB and rifampicin resistance. We identified only one study that evaluated the newest test version, Xpert MTB/RIF Ultra (Ultra), for TB meningitis. Fifty studies (76%) took place in low- or middle-income countries. Risk of bias was low for patient selection, index test, and flow and timing domains and was high or unclear for the reference standard domain (most of these studies decontaminated sterile specimens before culture inoculation). Regarding applicability, in the patient selection domain, we scored high or unclear concern for most studies because either patients were evaluated exclusively as inpatients at tertiary care centres, or we were not sure about the clinical settings.Pooled Xpert sensitivity (defined by culture) varied across different types of specimens (31% in pleural tissue to 97% in bone or joint fluid); Xpert sensitivity was > 80% in urine and bone or joint fluid and tissue. Pooled Xpert specificity (defined by culture) varied less than sensitivity (82% in bone or joint tissue to 99% in pleural fluid and urine). Xpert specificity was ≥ 98% in cerebrospinal fluid, pleural fluid, urine, and peritoneal fluid.Xpert testing in cerebrospinal fluidXpert pooled sensitivity and specificity (95% credible interval (CrI)) against culture were 71.1% (60.9% to 80.4%) and 98.0% (97.0% to 98.8%), respectively (29 studies, 3774 specimens; moderate-certainty evidence).For a population of 1000 people where 100 have TB meningitis on culture, 89 would be Xpert-positive: of these, 18 (20%) would not have TB (false-positives); and 911 would be Xpert-negative: of these, 29 (3%) would have TB (false-negatives).For TB meningitis, ultra sensitivity and specificity against culture (95% confidence interval (CI)) were 90% (55% to 100%) and 90% (83% to 95%), respectively (one study, 129 participants).Xpert testing in pleural fluidXpert pooled sensitivity and specificity (95% CrI) against culture were 50.9% (39.7% to 62.8%) and 99.2% (98.2% to 99.7%), respectively (27 studies, 4006 specimens; low-certainty evidence).For a population of 1000 people where 150 have pleural TB on culture, 83 would be Xpert-positive: of these, seven (8%) would not have TB (false-positives); and 917 would be Xpert-negative: of these, 74 (8%) would have TB (false-negatives).Xpert testing in urineXpert pooled sensitivity and specificity (95% CrI) against culture were 82.7% (69.6% to 91.1%) and 98.7% (94.8% to 99.7%), respectively (13 studies, 1199 specimens; moderate-certainty evidence).For a population of 1000 people where 70 have genitourinary TB on culture, 70 would be Xpert-positive: of these, 12 (17%) would not have TB (false-positives); and 930 would be Xpert-negative: of these, 12 (1%) would have TB (false-negatives).Xpert testing for rifampicin resistanceXpert pooled sensitivity (20 studies, 148 specimens) and specificity (39 studies, 1088 specimens) were 95.0% (89.7% to 97.9%) and 98.7% (97.8% to 99.4%), respectively (high-certainty evidence).For a population of 1000 people where 120 have rifampicin-resistant TB, 125 would be positive for rifampicin-resistant TB: of these, 11 (9%) would not have rifampicin resistance (false-positives); and 875 would be negative for rifampicin-resistant TB: of these, 6 (1%) would have rifampicin resistance (false-negatives).For lymph node TB, the accuracy of culture, the reference standard used, presented a greater concern for bias than in other forms of extrapulmonary TB. AUTHORS' CONCLUSIONS In people presumed to have extrapulmonary TB, Xpert may be helpful in confirming the diagnosis. Xpert sensitivity varies across different extrapulmonary specimens, while for most specimens, specificity is high, the test rarely yielding a positive result for people without TB (defined by culture). Xpert is accurate for detection of rifampicin resistance. For people with presumed TB meningitis, treatment should be based on clinical judgement, and not withheld solely on an Xpert result, as is common practice when culture results are negative.
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Affiliation(s)
- Mikashmi Kohli
- McGill UniversityDepartment of Epidemiology, Biostatistics and Occupational HealthMontrealCanada
| | - Ian Schiller
- McGill University Health Centre ‐ Research InstituteDivision of Clinical EpidemiologyMontrealCanada
| | - Nandini Dendukuri
- McGill University Health Centre ‐ Research InstituteDivision of Clinical EpidemiologyMontrealCanada
| | - Keertan Dheda
- University of Cape Town3 Centre for Lung Infection and Immunity Unit, Department of Medicine and UCT Lung InstituteCape TownSouth Africa
| | | | | | - Karen R Steingart
- Department of Clinical Sciences, Liverpool School of Tropical MedicineHonorary Research FellowPembroke PlaceLiverpoolUK
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Rice JP, Seifert M, Moser KS, Rodwell TC. Performance of the Xpert MTB/RIF assay for the diagnosis of pulmonary tuberculosis and rifampin resistance in a low-incidence, high-resource setting. PLoS One 2017; 12:e0186139. [PMID: 29016684 PMCID: PMC5633176 DOI: 10.1371/journal.pone.0186139] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 09/26/2017] [Indexed: 02/07/2023] Open
Abstract
Performance of the Xpert MTB/RIF assay, designed to simultaneously detect Mycobacterium tuberculosis complex (MTBC) and rifampin (RIF) resistance, has been well documented in low-resource settings with high TB-incidence. However, few studies have assessed its accuracy in low TB incidence settings. We evaluated the performance of Xpert MTB/RIF using clinical sputum specimens routinely collected from suspect pulmonary TB patients over a 4-year time period in San Diego County, California. Xpert MTB/RIF results were compared to acid-fast bacilli (AFB) smear microscopy, mycobacterial culture, and phenotypic drug susceptibility testing (DST). Of 751 sputum specimens, 134 (17.8%) were MTBC culture-positive and 2 (1.5%) were multidrug-resistant (MDR). For the detection of MTBC, Xpert MTB/RIF sensitivity was 89.6% (97.7% and 74.5% in smear-positive and -negative sputa, respectively) and specificity was 97.2%; while AFB smear sensitivity and specificity were 64.9% and 77.8%, respectively. Xpert MTB/RIF detected 35 of 47 smear-negative culture-positive specimens, and excluded 124 of 137 smear-positive culture-negative specimens. Xpert MTB/RIF also correctly excluded 99.2% (121/122) of nontuberculous mycobacteria (NTM) specimens, including all 33 NTM false-positives by smear microscopy. For the detection of RIF resistance, Xpert MTB/RIF sensitivity and specificity were 100% and 98.3%, respectively. Our findings demonstrate that Xpert MTB/RIF is able to accurately detect MTBC and RIF resistance in routinely collected respiratory specimens in a low TB-incidence setting, with comparable performance to that achieved in high-incidence settings; and suggest that under these conditions the assay has particular utility in detecting smear-negative TB cases, excluding smear-positive patients without MTBC disease, and differentiating MTBC from NTM.
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Affiliation(s)
- Jason P. Rice
- Division of Preventive Medicine, University of California, San Diego, California, United States of America
- * E-mail:
| | - Marva Seifert
- Division of Pulmonary, Critical Care and Sleep Medicine, University of California, San Diego, California, United States of America
| | - Kathleen S. Moser
- Tuberculosis Control and Refugee Health Program, County of San Diego Health and Human Services Agency, San Diego, California, United States of America
| | - Timothy C. Rodwell
- Division of Pulmonary, Critical Care and Sleep Medicine, University of California, San Diego, California, United States of America
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Molecular detection methods of resistance to antituberculosis drugs in Mycobacterium tuberculosis. Med Mal Infect 2017. [DOI: 10.1016/j.medmal.2017.04.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Rufai SB, Singh A, Singh J, Kumar P, Sankar MM, Singh S. Diagnostic usefulness of Xpert MTB/RIF assay for detection of tuberculous meningitis using cerebrospinal fluid. J Infect 2017; 75:125-131. [PMID: 28501491 DOI: 10.1016/j.jinf.2017.04.010] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 04/01/2017] [Accepted: 04/05/2017] [Indexed: 02/07/2023]
Abstract
OBJECTIVE Tuberculous meningitis (TBM) is the most severe form of extra-pulmonary tuberculosis (TB) due to association of diseases with high rates of mortality and morbidity. Diagnosis continues to be a clinical challenge as microbiological confirmation is rare and time consuming resulting in delayed treatment. Xpert MTB/RIF assay is a rapid and simple test, which has been endorsed by World Health Organization as an initial diagnostic test for the diagnosis of TBM. However, evidence still lacks for its performance on cerebrospinal fluid (CSF) for the diagnosis of TBM especially from India. METHODS A total of 267 CSF samples from patients with high clinico-radiological suspicion of TBM were included in this study. Ziehl-Neelsen (ZN) staining, BACTEC Mycobacterial Growth Indicator Tube (MGIT-960) culture system, and Xpert MTB/RIF assay (using cartridge version G4) were tested on all samples. RESULTS Of total 267 samples, all were negative for smear AFB and 52 (19.5%) were culture positive by MGIT-960 culture system. However, out of 52 (19.5%) cultures detected positive by MGIT-960, 5 (9.6%) were detected as resistant to rifampicin. Xpert MTB/RIF assay was positive in 38 (14.2%) samples and negative in 223 (83.5%) samples. Cartridge error was detected in 6 (2.2%) samples, which could not be repeated due to insufficient sample volume. The sensitivity and specificity of Xpert MTB/RIF assay in comparison to MGIT-960 was 55.1% (95%, CI: 40.2-69.3) and 94.8% (95%, CI: 90.9-97.4) respectively. Overall, Xpert MTB/RIF assay detected 38 (14.2%) as positive for MTB of which 4 (10.5%), 31 (81.6%) and 3 (7.9%) were found to be rifampicin resistant, sensitive and indeterminate respectively. CONCLUSION Xpert MTB/RIF assay showed lower sensitivity as compared to MGIT 960 culture for the diagnosis of TBM from CSF samples.
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Affiliation(s)
- Syed Beenish Rufai
- Division of Clinical Microbiology and Molecular Medicine, Department of Laboratory Medicine, All India Institute of Medical Sciences, New Delhi, India
| | - Amit Singh
- Division of Clinical Microbiology and Molecular Medicine, Department of Laboratory Medicine, All India Institute of Medical Sciences, New Delhi, India
| | - Jitendra Singh
- Division of Clinical Microbiology and Molecular Medicine, Department of Laboratory Medicine, All India Institute of Medical Sciences, New Delhi, India
| | - Parveen Kumar
- Division of Clinical Microbiology and Molecular Medicine, Department of Laboratory Medicine, All India Institute of Medical Sciences, New Delhi, India
| | - Manimuthu Mani Sankar
- Division of Clinical Microbiology and Molecular Medicine, Department of Laboratory Medicine, All India Institute of Medical Sciences, New Delhi, India
| | - Sarman Singh
- Division of Clinical Microbiology and Molecular Medicine, Department of Laboratory Medicine, All India Institute of Medical Sciences, New Delhi, India.
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- Division of Clinical Microbiology and Molecular Medicine, Department of Laboratory Medicine, All India Institute of Medical Sciences, New Delhi, India
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Moussa HS, Bayoumi FS, Ali AM. Evaluation of GeneXpert MTB/RIF assay for direct diagnosis of pulmonary tuberculosis. Saudi Med J 2017; 37:1076-81. [PMID: 27652357 PMCID: PMC5075370 DOI: 10.15537/smj.2016.10.14998] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Objectives: To evaluate the performance of GeneXpert MTB/RIF assay for direct diagnosis of pulmonary tuberculosis (PTB). Methods: This is a cross-sectional study conducted between October 2013 and February 2016 at Abbassaia Chest Hospital and Ain Shams University Hospital, Cairo, Egypt. Inclusion criteria were adults between 18 and 60 years with suspected PTB and classified into 5 clinical categories based on their clinical, radiological, and laboratory findings: confirmed TB, probable TB, possible TB, unlikely TB, and not TB. Two sputum samples from each participant were analyzed by GX and the results were compared by conventional culture. Results: In total, 218 participants were enrolled: 71 had confirmed TB; 112, highly probable TB; 20, probable TB; 10, unlikely TB; and 5, no TB. The sensitivity and specificity of the GX assay were 93% and 98.3% respectively. GeneXpert was positive in 93% of confirmed TB and 2.2% of probable TB cases. Conclusions: GeneXpert is a rapid and promising technique with good sensitivity (93%) and specificity (98.3%), but it cannot be used as a standalone PTB diagnostic tool. There is a need for more GX evaluation studies in countries with low TB incidence.
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Affiliation(s)
- Husseiny Sh Moussa
- Botany Department, Faculty of Women for Art, Science, and Education, Ain Shams University, Cairo, Egypt. E-mail.
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Greub G, Sahli R, Brouillet R, Jaton K. Ten years of R&D and full automation in molecular diagnosis. Future Microbiol 2016; 11:403-25. [PMID: 27028061 DOI: 10.2217/fmb.15.152] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A 10-year experience of our automated molecular diagnostic platform that carries out 91 different real-time PCR is described. Progresses and future perspectives in molecular diagnostic microbiology are reviewed: why automation is important; how our platform was implemented; how homemade PCRs were developed; the advantages/disadvantages of homemade PCRs, including the critical aspects of troubleshooting and the need to further reduce the turnaround time for specific samples, at least for defined clinical settings such as emergencies. The future of molecular diagnosis depends on automation, and in a novel perspective, it is time now to fully acknowledge the true contribution of molecular diagnostic and to reconsider the indication for PCR, by also using these tests as first-line assays.
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Affiliation(s)
- Gilbert Greub
- Institute of Microbiology, University of Lausanne & University Hospital Center, Lausanne, Switzerland
| | - Roland Sahli
- Institute of Microbiology, University of Lausanne & University Hospital Center, Lausanne, Switzerland
| | - René Brouillet
- Institute of Microbiology, University of Lausanne & University Hospital Center, Lausanne, Switzerland
| | - Katia Jaton
- Institute of Microbiology, University of Lausanne & University Hospital Center, Lausanne, Switzerland
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Opota O, Senn L, Prod'hom G, Mazza-Stalder J, Tissot F, Greub G, Jaton K. Added value of molecular assay Xpert MTB/RIF compared to sputum smear microscopy to assess the risk of tuberculosis transmission in a low-prevalence country. Clin Microbiol Infect 2016; 22:613-9. [DOI: 10.1016/j.cmi.2016.04.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 03/30/2016] [Accepted: 04/08/2016] [Indexed: 10/21/2022]
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Horita N, Yamamoto M, Sato T, Tsukahara T, Nagakura H, Tashiro K, Shibata Y, Watanabe H, Nagai K, Nakashima K, Ushio R, Ikeda M, Sakamaki K, Yoshiyama T, Kaneko T. Sensitivity and specificity of Cobas TaqMan MTB real-time polymerase chain reaction for culture-proven Mycobacterium tuberculosis: meta-analysis of 26999 specimens from 17 Studies. Sci Rep 2015; 5:18113. [PMID: 26648113 PMCID: PMC4673449 DOI: 10.1038/srep18113] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 11/12/2015] [Indexed: 11/08/2022] Open
Abstract
AbstractSince 2010, studies on the diagnostic accuracy of COBAS TaqMan MTB (CTM) have been frequently reported with an unignorable discrepancy. The key inclusion criterion for this systematic review was original studies that could provide sufficient data for calculating the sensitivity and the specificity of CTM for M tuberculosis (TB) or M tuberculosis complex. The reference test was Mycobacterium culture. We used bivariate model for meta-analyses. Of the 201 candidate articles, we finally identified 17 eligible articles.Concerning the respiratory specimens, 1900 culture positive specimens and 20983 culture negative specimens from 15 studies were assessed. This provided the summary estimate sensitivity of 0.808 (95% CI 0.758–0.850) and the summary estimate specificity of 0.990 (95% CI 0.981–0.994). The area under curve was 0.956. The diagnostic odds ratio was 459 (95% CI 261–805, I2 26%). For the smear positive respiratory specimens, the sensitivity was 0.952 (95% CI 0.926–0.969) and the specificity was 0.916 (95% CI 0.797–0.968). For the smear negative respiratory specimens, the sensitivity and the specificity were 0.600 (95% CI 0.459–0.726) and 0.989 (95% CI 0.981–0.993), respectively. The diagnostic accuracy was poorer for the non-respiratory specimens, than for the respiratory specimens, but was acceptable. We believe that the information obtained from this study will aid physicians’ decision making.
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Alvarez GG, Dyk DDV, Desjardlns M, Yasseen AS, Aaron SD, Cameron DW, Obed N, Baikie M, Pakhale S, Denklnger CM, Sohn H, Pal M. The Feasibility, Accuracy, and Impact of Xpert MTB/RIF Testing in a Remote Aboriginal Community in Canada. Chest 2015; 148:767-773. [PMID: 25789458 DOI: 10.1378/chest.14-2948] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Xpert MTB/RIF testing for Mycobacterium tuberculosis and rifampin resistance is being used extensively in countries with a high burden of TB. However, recent evidence suggests that it may not have the same accuracy or impact in high-income, low-burden TB countries. METHODS A prospective, pragmatic study was done between March 2012 and March 2014 to determine the feasibility, accuracy, and impact on TB disease management provided by the Xpert test in a remote, medically underserved, predominantly Inuit population in Iqaluit, Nunavut, Canada. RESULTS A total of 453 Xpert tests were run on sputum samples from 344 patients with suspected TB. Twenty-seven patients were identified as having active TB disease by culture. There were no cases of drug-resistant TB. Using culture as the gold standard, one Xpert test compared with one, two, or three sputum samples cultured per patient had a sensitivity of 85% (95% CI, 66%-95%) and a specificity of 99% (95% CI, 97%-100%) for detection of M tuberculosis. The indeterminate rate was 4.4% of all samples run. Treatment initiation was significantly shortened using Xpert vs the national standard of three smears (1.8 days vs 7.7 days, P < .007) and particularly shorter in smear-negative, culture-positive cases (1.8 days vs 37.1 days, P < .008). CONCLUSIONS In a predominantly Inuit population in a remote region of Canada where the burden of TB is high and no TB testing facilities are available, onsite Xpert testing was feasible and accurate and shortened the time to TB treatment initiation.
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Affiliation(s)
- Gonzalo G Alvarez
- Department of Medicine, Division of Respirology and Infectious Diseases, Ottawa Hospital Research Institute, University of Ottawa, Ottawa Hospital, Ottawa, ON.
| | - Deborah D Van Dyk
- Department of Medicine, Division of Respirology and Infectious Diseases, Ottawa Hospital Research Institute, University of Ottawa, Ottawa Hospital, Ottawa, ON
| | - Marc Desjardlns
- Department of Laboratory Medicine, Eastern Ontario Regional Laboratories, Ottawa, ON
| | - Abdool S Yasseen
- Department of Medicine, Division of Respirology and Infectious Diseases, Ottawa Hospital Research Institute, University of Ottawa, Ottawa Hospital, Ottawa, ON
| | - Shawn D Aaron
- Department of Medicine, Division of Respirology and Infectious Diseases, Ottawa Hospital Research Institute, University of Ottawa, Ottawa Hospital, Ottawa, ON
| | - D William Cameron
- Department of Medicine, Division of Respirology and Infectious Diseases, Ottawa Hospital Research Institute, University of Ottawa, Ottawa Hospital, Ottawa, ON
| | | | - Maureen Baikie
- Department of Health, Government of Nunavut, Iqaluit, NU
| | - Smita Pakhale
- Department of Medicine, Division of Respirology and Infectious Diseases, Ottawa Hospital Research Institute, University of Ottawa, Ottawa Hospital, Ottawa, ON
| | - Claudla M Denklnger
- Respiratory Epidemiology and Clinical Research Unit and McGill International Tuberculosis Centre, McGill University, Montreal, QC, Canada
| | - Hojoon Sohn
- Respiratory Epidemiology and Clinical Research Unit and McGill International Tuberculosis Centre, McGill University, Montreal, QC, Canada
| | - Madhukar Pal
- Respiratory Epidemiology and Clinical Research Unit and McGill International Tuberculosis Centre, McGill University, Montreal, QC, Canada
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Maynard-Smith L, Larke N, Peters JA, Lawn SD. Diagnostic accuracy of the Xpert MTB/RIF assay for extrapulmonary and pulmonary tuberculosis when testing non-respiratory samples: a systematic review. BMC Infect Dis 2014; 14:709. [PMID: 25599808 PMCID: PMC4298952 DOI: 10.1186/s12879-014-0709-7] [Citation(s) in RCA: 131] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 12/11/2014] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Although the evidence base regarding the use of the Xpert MTB/RIF assay for diagnosis of pulmonary tuberculosis (TB) when testing respiratory samples is well established, the evidence base for its diagnostic accuracy for extrapulmonary and sputum-scarce pulmonary TB when testing non-respiratory samples is less clearly defined. METHODS A systematic literature search of 7 electronic databases (Medline, EMBASE, ISI Web of Science, BIOSIS, Global Health Database, Scopus and Cochrane Database) was conducted to identify studies of the diagnostic accuracy of the Xpert assay when testing non-respiratory samples compared with a culture-based reference standard. Data were extracted and study quality was assessed using the QUADAS-2 tool. Sensitivities and specificities were calculated on a per-sample basis, stratified by sample type and smear microscopy status and summarised using forest plots. Pooled estimates were calculated for groups with sufficient data. RESULTS Twenty-seven studies with a total of 6,026 non-respiratory samples were included. Among the 23 studies comparing Xpert and culture done on the same samples, sensitivity was very heterogeneous with a median sensitivity of 0.83 (IQR, 0.68-0.94) whereas specificities were typically very high (median, 0.98; IQR, 0.89-1.00). The pooled summary estimates of sensitivity when testing smear-positive and smear-negative samples were 0.95 (95% CI 0.91-1.00) and 0.69 (95% CI 0.60-0.80), respectively. Pooled summary estimates of sensitivity varied substantially between sample types: lymph node tissue, 0.96 (95% CI, 0.72-0.99); tissue samples of all types, 0.88 (95% CI, 0.76-0.94); pleural fluid, 0.34 (95% CI, 0.24-0.44); gastric aspirates for diagnosis of sputum-scarce pulmonary TB, 0.78 (IQR, 0.68 - 0.85). Median sensitivities when testing cerebrospinal fluid and non-pleural serous fluid samples were 0.85 (IQR, 0.75-1.00) and 0.67 (IQR, 0.00-1.00), respectively. CONCLUSION Xpert detects with high specificity the vast majority of EPTB cases with smear-positive non-respiratory samples and approximately two-thirds of those with smear-negative samples. Xpert is a useful rule-in diagnostic test for EPTB, especially when testing cerebrospinal fluid and tissue samples. In addition, it has a high sensitivity for detecting pulmonary TB when using gastric aspirate samples. These findings support recent WHO guidelines regarding the use of Xpert for TB diagnosis from non-respiratory samples.
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Affiliation(s)
- Laura Maynard-Smith
- />Department of Clinical Research, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT UK
| | - Natasha Larke
- />MRC Tropical Epidemiology Group, Faculty of Epidemiology and Public Health, London School of Hygiene and Tropical Medicine, London, UK
| | - Jurgens A Peters
- />Department of Clinical Research, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT UK
| | - Stephen D Lawn
- />Department of Clinical Research, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT UK
- />The Desmond Tutu HIV Centre, Institute for Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
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Huh HJ, Jeong BH, Jeon K, Koh WJ, Ki CS, Lee NY. Performance evaluation of the Xpert MTB/RIF assay according to its clinical application. BMC Infect Dis 2014; 14:589. [PMID: 25395048 PMCID: PMC4247199 DOI: 10.1186/s12879-014-0589-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 10/24/2014] [Indexed: 01/20/2023] Open
Abstract
Background The Xpert MTB/RIF assay (Xpert assay; Cepheid, Sunnyvale, CA) is becoming the test of choice for the rapid diagnosis of tuberculosis and rifampin (RIF) resistance. The aim of this study was to evaluate the performance of the Xpert assay with respect to its clinical application at a tertiary care hospital in Korea, a country with an intermediate tuberculosis burden and high-resource. Methods A total of 303 Xpert assay results from 109 smear-positive and 194 smear-negative respiratory specimens were retrospectively reviewed. Based on patients’ medical records, four categories of clinical applications of the Xpert assay were identified: (1) the diagnosis of pulmonary tuberculosis in patients with a high probability of pulmonary tuberculosis according to their clinical and radiological features; (2) the exclusion of tuberculosis in clinically indeterminate patients for pulmonary tuberculosis; (3) the differentiation of Mycobacterium tuberculsosis (MTB) from nontuberculous mycobacteria in a smear-positive specimen; and (4) the diagnosis of RIF resistance. Standard culture and drug susceptibility tests were used as reference methods. Results The sensitivity of the Xpert assay for MTB detection in category 1 was 89.8% (95% confidence interval [CI], 78.5-95.8%), but 66.7% (95% CI, 12.5-98.2%) in category 2. The positive predictive values ranged from 33.3% (95% CI, 6.0-75.9%) in category 2 to 91.3% and 91.7% in categories 1 and 3, respectively. The negative predictive values were over 90% in all categories. The Xpert assay correctly detected RIF resistance in six of the seven (85.7%) isolates tested. Conclusions The Xpert assay exhibited variable performance according to its clinical application; this finding cautions that careful interpretation for the results of this assay would be needed according to its intended purpose. Electronic supplementary material The online version of this article (doi:10.1186/s12879-014-0589-x) contains supplementary material, which is available to authorized users.
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Shinnick TM, Starks AM, Alexander HL, Castro KG. Evaluation of the Cepheid Xpert MTB/RIF assay. Expert Rev Mol Diagn 2014; 15:9-22. [PMID: 25373876 DOI: 10.1586/14737159.2015.976556] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The lack of capacity to provide laboratory confirmation of a diagnosis of tuberculosis disease (TB) is contributing to enormous gaps in the ability to find, treat and follow TB patients. WHO estimates that globally only about 57% of the notified new cases of pulmonary TB in 2012 and about 19% of rifampicin-resistant TB cases were laboratory confirmed. The Cepheid Xpert(®) MTB/RIF assay has been credited with revolutionizing laboratory testing to aid in the diagnosis of TB and rifampicin-resistant TB. This semi-automated test can detect both the causative agent of TB and mutations that confer rifampicin resistance from clinical specimens within 2 h after starting the test. In this article, we review the performance of the test, its pathway to regulatory approval and endorsement, guidelines for its use and lessons learned from the implementation of the test in low-burden, high-resource countries and in high-burden, low-resource countries.
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Affiliation(s)
- Thomas M Shinnick
- Division of Tuberculosis Elimination, National Center for HIV, Viral Hepatitis, STD and TB Prevention, Centers for Disease Control and Prevention, Atlanta, GA, USA 30333
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Performance of the Xpert MTB/RIF assay on nonrespiratory specimens and accuracy of this assay for detection of rifampin resistance in a low-prevalence setting. J Clin Microbiol 2014; 52:706. [PMID: 24478523 DOI: 10.1128/jcm.02591-13] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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21
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Reply to "performance of the Xpert MTB/RIF assay on nonrespiratory specimens and accuracy of this assay for detection of rifampin resistance in a low-prevalence setting". J Clin Microbiol 2014; 52:707. [PMID: 24478524 DOI: 10.1128/jcm.03074-13] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Evaluation of GeneXpert MTB/RIF for the detection of Mycobacterium tuberculosis and resistance to rifampin in clinical specimens. J Infect 2013; 68:338-43. [PMID: 24296493 DOI: 10.1016/j.jinf.2013.11.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 11/19/2013] [Accepted: 11/21/2013] [Indexed: 11/22/2022]
Abstract
OBJECTIVES GeneXpert (GX) is a novel real-time polymerase chain reaction assay for the simultaneous detection of Mycobacterium tuberculosis (MTB) and resistance to rifampin (RIF). We evaluated the performance of GX for direct detection of MTB in respiratory and non-respiratory specimens and assessed the ability of the assay to detect resistance to RIF in non-tuberculosis (TB) endemic country. METHODS We analyzed 595 clinical samples in a 1550-bed tertiary hospital in Madrid, Spain. Specimens were processed using GX, auramine smear, conventional culture, and drug phenotypic susceptibility testing (DST) with MGIT SIRE (BD). RESULTS Of the 595 clinical samples, 305 (51.3%) were non-respiratory and 290 (48.7%) were respiratory. In total, MTB was isolated in 81 specimens, 71 of which were positive with GX. The sensitivity, specificity, PPV, and NPV of the GX were: 97.1%, 98.6%, 95.7% and 99.1% for respiratory samples and 33.3%, 99.7%, 80.0% and 97.3% for non-respiratory. GX detected 8 RIF-resistant samples, but only 5 were confirmed by DST. CONCLUSIONS GX is an accurate, easy-to-apply and rapid test to detect MTB, especially in smear-positive respiratory samples. Although is a useful tool for the rapid identification of RIF-resistant MTB strains, the rifampin resistant results should be confirmed by DST.
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