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Hu X, Shang M, Chen X, Xie Y, Ye Y, Zhou J, Song X, Lu X, Ying B, Wang L. Evaluation of three rapid assays for Mycobacterium tuberculosis complex detection in a comprehensive hospital from West China. Clin Biochem 2014; 48:79-84. [PMID: 25444951 DOI: 10.1016/j.clinbiochem.2014.10.003] [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: 07/24/2014] [Revised: 09/26/2014] [Accepted: 10/01/2014] [Indexed: 02/05/2023]
Abstract
OBJECTIVES To assess the capacity of rapid and accurate confirmation of the Mycobacterium tuberculosis complex (MTBC) in a Chinese clinical laboratory. DESIGN AND METHODS This prospective study investigated three rapid assays, the Amplified Mycobacterium Tuberculosis Direct (MTD) test, real-time PCR, and acid-fast bacilli (AFB) smear, for direct detection of MTBC in a large consecutive series of different clinical specimens. Performance parameters were estimated and compared overall and for separate specimen categories using a combined reference gold standard. RESULTS The overall sensitivities were similar for MTD and real-time PCR (62.26% vs. 58.49%), significantly higher than those of AFB smear (31.13%). Among three assays, MTD had a satisfactory sensitivity in respiratory specimen (73.33%) and a nearly perfect detection for smear-positive samples (96.97%). Real-time PCR showed a high positive rate (58.97%) in regard to nonrespiratory specimen. A combination of molecular assays with conventional methods reached marked additive diagnostic values (sensitivity up to 76.42%), higher than each method individually. All detection systems showed excellent specificities (>96.00%). CONCLUSIONS The present study indicated that our lab had a moderate diagnostic performance for tuberculosis. Quality guarantee for specimen pretreatment, as well as combination analysis, will enable these assays to better incorporate into the routine laboratory workflow in China.
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Affiliation(s)
- Xuejiao Hu
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu 610041, PR China
| | - Mengqiao Shang
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu 610041, PR China
| | - Xuerong Chen
- Division of Pulmonary Disease, Department of Respiratory Medicine, West China Hospital, Sichuan University, Chengdu 610041, PR China
| | - Yi Xie
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu 610041, PR China
| | - Yuanxin Ye
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu 610041, PR China
| | - Juan Zhou
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu 610041, PR China
| | - Xingbo Song
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu 610041, PR China
| | - Xiaojun Lu
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu 610041, PR China
| | - Binwu Ying
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu 610041, PR China.
| | - Lanlan Wang
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu 610041, PR China.
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Hofmann-Thiel S, Hoffmann H. Evaluation of Fluorotype MTB for detection of Mycobacterium tuberculosis complex DNA in clinical specimens from a low-incidence country. BMC Infect Dis 2014; 14:59. [PMID: 24498967 PMCID: PMC3922020 DOI: 10.1186/1471-2334-14-59] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2013] [Accepted: 01/30/2014] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND With Fluorotype MTB (FT MTB, HAIN Lifesciences, Germany) a new semi-automated assay for detection of M. tuberculosis complex (MTBC) in clinical specimens has been introduced. In a prospective study, we evaluated the diagnostic performance of FT MTB in a routine diagnostic setting in a low-incidence country. METHODS A total of 1039 respiratory specimens received for routine mycobacteriology diagnostics were analysed by FT MTB. Results were compared to those of culture, microscopy and clinical diagnosis. 61 specimens were excluded from further analysis due to bacterial contamination of cultures. RESULTS FT MTB detected 52 of 59 TB specimens (45 culture-positive with MTBC, 7 with clinical diagnosis of TB). With 902 of 912 non-TB specimens (884 culture-negative, 18 with growth of non-tuberculous mycobacteria) FT MTB was negative; discrepant positive FT MTB results were found with 10 specimens. Overall sensitivity, specificity, positive and negative predictive values were 88.1%, 98.9%, 83.8% and 99.2%. Sensitivity rates for smear-positive and smear-negative TB specimens were 100% and 56.3%, respectively. Seven of 978 samples (0.7%) yielded invalid FT MTB results. CONCLUSIONS FT MTB is a new accurate, half automated assay for rapidly diagnosing TB and suitable for larger series of samples. Performance characteristics were found to be similar to those of other commercial NAATs. Its sensitivity in paucibacillary, smear-negative specimens and its utility for TB diagnostics in high-incidence settings needs to be addressed in further studies.
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Affiliation(s)
- Sabine Hofmann-Thiel
- synlab MVZ Gauting, IML red, WHO Supranational Reference Laboratory of Tuberculosis, Robert-Koch-Allee 2, 82131 Gauting, Germany.
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Novel real-time simultaneous amplification and testing method to accurately and rapidly detect Mycobacterium tuberculosis complex. J Clin Microbiol 2012; 50:646-50. [PMID: 22205804 DOI: 10.1128/jcm.05853-11] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The aim of this study was to establish and evaluate a simultaneous amplification and testing method for detection of the Mycobacterium tuberculosis complex (SAT-TB assay) in clinical specimens by using isothermal RNA amplification and real-time fluorescence detection. In the SAT-TB assay, a 170-bp M. tuberculosis 16S rRNA fragment is reverse transcribed to DNA by use of Moloney murine leukemia virus (M-MLV) reverse transcriptase, using specific primers incorporating the T7 promoter sequence, and undergoes successive cycles of amplification using T7 RNA polymerase. Using a real-time PCR instrument, hybridization of an internal 6-carboxyfluorescein-4-[4-(dimethylamino)phenylazo] benzoic acid N-succinimidyl ester (FAM-DABCYL)-labeled fluorescent probe can be used to detect RNA amplification. The SAT-TB assay takes less than 1.5 h to perform, and the sensitivity of the assay for detection of M. tuberculosis H37Rv is 100 CFU/ml. The TB probe has no cross-reactivity with nontuberculous mycobacteria or other common respiratory tract pathogens. For 253 pulmonary tuberculosis (PTB) specimens and 134 non-TB specimens, the SAT-TB results correlated with 95.6% (370/387 specimens) of the Bactec MGIT 960 culture assay results. The sensitivity, specificity, and positive and negative predictive values of the SAT-TB test for the diagnosis of PTB were 67.6%, 100%, 100%, and 62.0%, respectively, compared to 61.7%, 100%, 100%, and 58.0% for Bactec MGIT 960 culture. For PTB diagnosis, the sensitivities of the SAT-TB and Bactec MGIT 960 culture methods were 97.6% and 95.9%, respectively, for smear-positive specimens and 39.2% and 30.2%, respectively, for smear-negative specimens. In conclusion, the SAT-TB assay is a novel, simple test with a high specificity which may enhance the detection rate of TB. It is therefore a promising tool for rapid diagnosis of M. tuberculosis infection in clinical microbiology laboratories.
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Performance assessment of the CapitalBio mycobacterium identification array system for identification of mycobacteria. J Clin Microbiol 2011; 50:76-80. [PMID: 22090408 DOI: 10.1128/jcm.00320-11] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The CapitalBio Mycobacterium identification microarray system is a rapid system for the detection of Mycobacterium tuberculosis. The performance of this system was assessed with 24 reference strains, 486 Mycobacterium tuberculosis clinical isolates, and 40 clinical samples and then compared to the "gold standard" of DNA sequencing. The CapitalBio Mycobacterium identification microarray system showed highly concordant identification results of 100% and 98.4% for Mycobacterium tuberculosis complex (MTC) and nontuberculous mycobacteria (NTM), respectively. The sensitivity and specificity of the CapitalBio Mycobacterium identification array for identification of Mycobacterium tuberculosis isolates were 99.6% and 100%, respectively, for direct detection and identification of clinical samples, and the overall sensitivity was 52.5%. It was 100% for sputum, 16.7% for pleural fluid, and 10% for bronchoalveolar lavage fluid, respectively. The total assay was completed in 6 h, including DNA extraction, PCR, and hybridization. The results of this study confirm the utility of this system for the rapid identification of mycobacteria and suggest that the CapitalBio Mycobacterium identification array is a molecular diagnostic technique with high sensitivity and specificity that has the capacity to quickly identify most mycobacteria.
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Kim JY, Ferraro MJ, Branda JA. False-negative results obtained with the Gen-Probe Amplified Mycobacterium tuberculosis direct test caused by unrecognized inhibition of the amplification reaction. J Clin Microbiol 2009; 47:2995-7. [PMID: 19587300 PMCID: PMC2738107 DOI: 10.1128/jcm.00966-09] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2009] [Revised: 06/14/2009] [Accepted: 07/01/2009] [Indexed: 11/20/2022] Open
Abstract
The Gen-Probe Amplified Mycobacterium tuberculosis direct test is widely used in the diagnosis of tuberculosis. Specimens may contain amplification inhibitors, potentially leading to false-negative results if unrecognized. We report a failure to detect inhibition, despite adherence to the inhibition testing guidelines provided on the label, and recommend changes.
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Affiliation(s)
- Ji Yeon Kim
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, Boston, MA 02114, USA
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6
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Evaluation of GenoType mycobacteria direct assay in comparison with Gen-Probe Mycobacterium tuberculosis amplified direct test and GenoType MTBDRplus for direct detection of Mycobacterium tuberculosis complex in clinical samples. J Clin Microbiol 2009; 47:2601-3. [PMID: 19553580 DOI: 10.1128/jcm.02351-08] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Three molecular assays were evaluated for the direct detection of Mycobacterium tuberculosis complex bacteria in 125 respiratory and 22 nonrespiratory samples. The overall sensitivities obtained were as follows: GenoType MTBDRplus, 97.9%; GenoType Mycobacteria Direct, 93.7%; Gen-Probe Mycobacterium tuberculosis Amplified Direct Test, 89.6%. The specificity of the assays used was 100%.
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Sener AG, Kurultay N, Afsar I. Evaluation of the results of Mycobacterium tuberculosis direct test (MTD) and Mycobacterial culture in urine samples. Braz J Microbiol 2008; 39:673-5. [PMID: 24031287 PMCID: PMC3768455 DOI: 10.1590/s1517-838220080004000014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Revised: 04/09/2008] [Accepted: 11/02/2008] [Indexed: 11/22/2022] Open
Abstract
Tuberculosis remains a public health problem in Turkey. Rapid detection of Mycobacterium tuberculosis plays a key role in control of infection. In this article, the Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test (MTD) was evaluated for detection of M. tuberculosis in urine samples. The performance of the MTD was very good and appropriate for routine laboratory diagnosis.
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Affiliation(s)
- Asli Gamze Sener
- Ataturk Training and Research Hospital, Microbiology and Clinical Microbiology Laboratory Izmir/Turkey
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8
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Ling DI, Flores LL, Riley LW, Pai M. Commercial nucleic-acid amplification tests for diagnosis of pulmonary tuberculosis in respiratory specimens: meta-analysis and meta-regression. PLoS One 2008; 3:e1536. [PMID: 18253484 PMCID: PMC2212137 DOI: 10.1371/journal.pone.0001536] [Citation(s) in RCA: 151] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2007] [Accepted: 01/06/2008] [Indexed: 11/22/2022] Open
Abstract
Background Hundreds of studies have evaluated the diagnostic accuracy of nucleic-acid amplification tests (NAATs) for tuberculosis (TB). Commercial tests have been shown to give more consistent results than in-house assays. Previous meta-analyses have found high specificity but low and highly variable estimates of sensitivity. However, reasons for variability in study results have not been adequately explored. We performed a meta-analysis on the accuracy of commercial NAATs to diagnose pulmonary TB and meta-regression to identify factors that are associated with higher accuracy. Methodology/Principal Findings We identified 2948 citations from searching the literature. We found 402 articles that met our eligibility criteria. In the final analysis, 125 separate studies from 105 articles that reported NAAT results from respiratory specimens were included. The pooled sensitivity was 0.85 (range 0.36–1.00) and the pooled specificity was 0.97 (range 0.54–1.00). However, both measures were significantly heterogeneous (p<.001). We performed subgroup and meta-regression analyses to identify sources of heterogeneity. Even after stratifying by type of commercial test, we could not account for the variability. In the meta-regression, the threshold effect was significant (p = .01) and the use of other respiratory specimens besides sputum was associated with higher accuracy. Conclusions/Significance The sensitivity and specificity estimates for commercial NAATs in respiratory specimens were highly variable, with sensitivity lower and more inconsistent than specificity. Thus, summary measures of diagnostic accuracy are not clinically meaningful. The use of different cut-off values and the use of specimens other than sputum could explain some of the observed heterogeneity. Based on these observations, commercial NAATs alone cannot be recommended to replace conventional tests for diagnosing pulmonary TB. Improvements in diagnostic accuracy, particularly sensitivity, need to be made in order for this expensive technology to be worthwhile and beneficial in low-resource countries.
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Affiliation(s)
- Daphne I. Ling
- Division of Epidemiology, School of Public Health, University of California, Berkeley, California, United States of America
| | - Laura L. Flores
- Division of Pulmonary and Critical Care Medicine, San Francisco General Hospital, San Francisco, California, United States of America
| | - Lee W. Riley
- Division of Epidemiology, School of Public Health, University of California, Berkeley, California, United States of America
- Division of Infectious Diseases, School of Public Health, University of California, Berkeley, California, United States of America
| | - Madhukar Pai
- Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, Quebec, Canada
- * To whom correspondence should be addressed. E-mail:
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Wang JY, Lee LN, Lai HC, Hsu HL, Jan IS, Yu CJ, Hsueh PR, Yang PC. Performance assessment of the Capilia TB assay and the BD ProbeTec ET system for rapid culture confirmation of Mycobacterium tuberculosis. Diagn Microbiol Infect Dis 2007; 59:395-9. [PMID: 17878064 DOI: 10.1016/j.diagmicrobio.2007.06.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2007] [Revised: 06/14/2007] [Accepted: 06/19/2007] [Indexed: 11/20/2022]
Abstract
Because of the increasing numbers of nontuberculous mycobacterial isolates from clinical specimens, rapid and accurate methods for culture confirmation of Mycobacterium tuberculosis are urgently needed. The study evaluated the performance of the Capilia TB immunochromatographic assay (TAUNS, Numazu, Japan) for culture confirmation of M. tuberculosis using 242 culture-positive liquid media in 2 mycobacterial laboratories from November 2005 to February 2006. Among the 242 samples, 183 were also tested with the BD ProbeTec ET (CTB) assay (Becton Dickinson, Sparks, MD). The results of both assays were compared to the culture results and to each other. The overall sensitivity and specificity of the Capilia TB assay were 98.6% and 97.9%, respectively, and for the CTB assay were 97.3% and 97.1%, respectively. The positive and negative predictive values for the Capilia TB assay were 98.6% and 97.9%, respectively, and for the CTB assay were 98.2% and 95.8%, respectively. Among the 183 samples tested with both assays, 8 had discrepant results, including Capilia-TB-false-positive in 2, CTB-false-positive in another 2, CTB-false-negative in 2, Capilia TB-false-negative in 1, and both assays with false-negative results in the remaining one. This study demonstrated that the Capilia TB assay has a similar diagnostic value with the CTB assay. In addition, with the immunochromatographic method, it is less time-consuming and does not require other laboratory equipment.
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Affiliation(s)
- Jann-Yuan Wang
- Internal Medicine, National Taiwan University Hospital, Taipei 100, Taiwan
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10
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Osores F, Nolasco O, Verdonck K, Arévalo J, Ferrufino JC, Agapito J, Huayanay L, Gotuzzo E, Maguiña C. Clinical Evaluation of a 16S Ribosomal RNA Polymerase Chain Reaction Test for the Diagnosis of Lymph Node Tuberculosis. Clin Infect Dis 2006; 43:855-9. [PMID: 16941366 DOI: 10.1086/507536] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2006] [Accepted: 06/13/2006] [Indexed: 11/03/2022] Open
Abstract
UNLABELLED Reports on the sensitivity of polymerase chain reaction (PCR) for the diagnosis of lymph node tuberculosis (TB) show divergent results. We evaluated the accuracy of the Roche Amplicor Mycobacterium tuberculosis PCR test with lymph node aspirate and biopsy samples. METHODS The study was conducted at a public reference hospital in Lima, Peru. From the period of January 2003 to January 2004, we included patients who had lymphadenopathy and in whom the attending physician suspected TB. Aspirate and biopsy samples were submitted for culturing in Lowenstein-Jensen medium, for histopathologic testing, and for PCR. The sensitivity and specificity of PCR were calculated against a reference standard based on histopathologic findings and culture. RESULTS Our study included 154 patients. Median age was 29 years (interquartile range, 21-40 years); 97 patients (62.9%) were men. Twenty-nine patients (18.8%) had acid fast bacilli-positive histopathologic findings, and 44 (28.6%) had a positive culture result. Using the combination of histopathologic findings and culture as reference standard, 55 patients (35.7%) had a diagnosis of tuberculous lymphadenitis. The sensitivity of the PCR test was 58.2%, and the specificity was 93.9%. For biopsy tissue only, the sensitivity of PCR was 52.7%, and the specificity was 97.0%. For aspirate samples only, the sensitivity of PCR was 47.3%, and the specificity was 96.0%. CONCLUSION The Amplicor PCR test revealed low sensitivity and high specificity for the diagnosis of lymph node TB. The sensitivity was higher in cases in which the bacillary load was high--in acid fast bacilli-positive samples and among HIV-infected patients. Considering the results of microbiological and PCR tests together, there was still a patient group in whom no final diagnosis could be established.
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Affiliation(s)
- Fernando Osores
- Institute of Tropical Medicine Alexander von Humboldt, Lima, Peru.
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11
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Soo PC, Horng YT, Hsueh PR, Shen BJ, Wang JY, Tu HH, Wei JR, Hsieh SC, Huang CC, Lai HC. Direct and Simultaneous Identification of Mycobacterium tuberculosis complex (MTBC) and Mycobacterium tuberculosis (MTB) by Rapid Multiplex nested PCR-ICT assay. J Microbiol Methods 2006; 66:440-8. [PMID: 16516314 DOI: 10.1016/j.mimet.2006.01.010] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2005] [Revised: 01/18/2006] [Accepted: 01/23/2006] [Indexed: 11/24/2022]
Abstract
The Mycobacterium tuberculosis (MTB) shows different virulence and host infection range from other members of the M. tuberculosis complex (MTBC). Differential identification of MTB from MTBC is thus important in certain occasions. The currently commercially available molecular assays which use either IS6110 or 16S rDNA fragment as identification targets are mainly designed for identifying MTBC but not for MTB. Comparative genomic DNA analysis has provided valuable information on regions of difference (RD) present in MTB but not in other members of the MTBC. RD9 region is further suggested to be a potential target for differential identification of MTB from MTBC. In this study, using IS6110 and Rv3618 (belong to RD9) as the specific identification targets for MTBC and MTB, respectively, we developed and tested a multiplex nested PCR-ICT (immuno-chromatography test) assay for simultaneously and directly detecting not only MTBC but also MTB from 1500 clinical sputum specimens. The results were compared with traditional culture and biochemical identification results together with patients' clinical assessments. This assay showed a 95.5% sensitivity, 97.9% specificity, 2.1% false positive rate and 4.5% false negative rate towards detection of MTBC, and a 93.0% sensitivity, 99.8% specificity, 0.2% false positive rate and 7.0% false negative rate for detection of MTB. This detection system shows great potential in clinical application.
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Affiliation(s)
- Po-Chi Soo
- Department of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University College of Medicine, No. 1 Chan-Der Street, Taipei 100, Taiwan, ROC
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Pollock N, Westerling J, Sloutsky A. Specimen Dilution Increases the Diagnostic Utility of the Gen-Probe Mycobacterium Tuberculosis Direct Test. Am J Clin Pathol 2006. [DOI: 10.1309/jbqhwc6h4yn6f67q] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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13
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Wang JY, Lee LN, Hsu HL, Hsueh PR, Luh KT. Performance assessment of the DR. MTBC Screen assay and the BD ProbeTec ET system for direct detection of Mycobacterium tuberculosis in respiratory specimens. J Clin Microbiol 2006; 44:716-9. [PMID: 16517844 PMCID: PMC1393081 DOI: 10.1128/jcm.44.3.716-719.2006] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The performance of the DR. MTBC PCR-based assay and the BD ProbeTec ET Mycobacterium tuberculosis Complex Direct Detection (DTB) assay for the direct detection of Mycobacterium tuberculosis was evaluated using 1,066 consecutive clinical respiratory samples collected from 494 patients who did not have old cases of pulmonary tuberculosis and were not receiving antituberculosis treatment at National Taiwan University Hospital from January to February 2005. The results of both assays were compared to the "gold standard" of combined culture results and clinical diagnosis. The overall sensitivity and specificity of the DR. MTBC Screen assay were 56.6% and 98.9%, respectively, and of the DTB assay were 63.2% and 98.4%, respectively. The positive and negative predictive values for the DR. MTBC Screen assay were 84.5% and 95.4%, respectively, and for the DTB assay were 81.7% and 96.0%, respectively. The DR. MTBC Screen assay produced 11 false-positive results for 11 patients, including three samples yielding non-M. tuberculosis mycobacteria (one each for M. abscessus, a mixture of M. abscessus and M. chelonae, and unidentified non-tuberculosis mycobacteria). The DTB assay produced 15 false-positive results for 13 patients, including five samples from four patients yielding non-tuberculosis mycobacteria (two for M. abscessus, one for a mixture of M. abscessus and M. chelonae, and two for unidentified non-tuberculosis mycobacteria). This study demonstrated that the DR. MTBC Screen assay has a similar diagnostic value but fewer false-positive results than the DTB assay for respiratory specimens.
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Affiliation(s)
- Jann-Yuan Wang
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
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14
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Greco S, Girardi E, Navarra A, Saltini C. Current evidence on diagnostic accuracy of commercially based nucleic acid amplification tests for the diagnosis of pulmonary tuberculosis. Thorax 2006; 61:783-90. [PMID: 16738037 PMCID: PMC2117107 DOI: 10.1136/thx.2005.054908] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Even though commercial nucleic acid amplification tests (NAATs) have become the most frequently used molecular tests for laboratory diagnosis of pulmonary tuberculosis (TB), published studies report variable estimates of their diagnostic accuracy. We analysed the accuracy of commercial NAATs for the diagnosis of pulmonary TB in smear positive and smear negative respiratory samples using culture as a reference standard. METHODS English language studies reporting data sufficient for calculating sensitivity and specificity of commercial NAATs on smear positive and/or smear negative respiratory samples were included. Meta-regression was used to analyse associations with reference test quality, the prevalence of TB, sample and test type. Predictive values for different levels of pre-test probability were quantified using Bayes' approach. RESULTS Sixty three journal articles published between 1995 and 2004 met the inclusion criteria. Pooled sensitivity and specificity were 0.96 and 0.85 among smear positive samples and 0.66 and 0.98 among smear negative samples. The number of culture media used as reference test, the inclusion of bronchial samples, and the TB prevalence were found to influence the reported accuracy. The test type had no effect on the diagnostic odds ratio but seemed to be correlated with sensitivity or specificity, probably via a threshold effect. CONCLUSIONS Commercial NAATs can be confidently used to exclude TB in patients with smear positive samples in which environmental mycobacteria infection is suspected and to confirm TB in a proportion of smear negative cases. The methodological characteristics of primary studies have a considerable effect on the reported diagnostic accuracy.
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Affiliation(s)
- S Greco
- Dipartimento di Malattie Polmonari, Azienda Ospedaliera San Camillo-Forlanini, Rome, Italy.
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15
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Goessens WHF, de Man P, Koeleman JGM, Luijendijk A, te Witt R, Endtz HP, van Belkum A. Comparison of the COBAS AMPLICOR MTB and BDProbeTec ET assays for detection of Mycobacterium tuberculosis in respiratory specimens. J Clin Microbiol 2005; 43:2563-6. [PMID: 15956364 PMCID: PMC1151882 DOI: 10.1128/jcm.43.6.2563-2566.2005] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The performances of the BDProbeTec ET (Becton Dickinson) and COBAS AMPLICOR MTB (Roche) were retrospectively evaluated for detecting Mycobacterium tuberculosis complex in various respiratory specimens. The BACTEC and MGIT liquid culture system (Becton Dickinson) was used as a reference method. A total of 824 respiratory specimens, comprised of sputa, bronchoalveolar lavage fluid, and bronchial and tracheal aspirates from 580 patients, were evaluated. Out of 824 clinical specimens, 109 specimens from 43 patients were culture positive for M. tuberculosis. Of these 109 specimens, 67 were smear positive, 85 were positive by the COBAS AMPLICOR MTB test, and 94 were positive by the BDProbeTec ET. Of the 715 culture-negative specimens, 17 were positive by the auramine staining, 11 were positive by the COBAS AMPLICOR MTB test, and 12 were positive by the BDProbeTec ET. After discrepancy analysis and review of the patients' clinical data, 130 specimens from 50 patients were considered "true-positive" specimens. This resulted in the following sensitivities: microscopy, 61.5%; COBAS AMPLICOR MTB test, 78.0%; and BDProbeTec ET, 86.2%. The specificities of each system, based on the clinical diagnosis, were 99.7% for microscopy, 99.9% for the COBAS AMPLICOR MTB test, and 99.9% for the BDProbeTec ET. The data presented represent a considerable number of specimens evaluated with a considerable number of culture- and auramine-positive and culture-positive and auramine-negative results and therefore give a realistic view of how the data should be interpreted in a daily routine situation. Specifically, the data with regard to the culture-positive and auramine-negative specimens are useful, because in a routine situation, auramine-negative specimens are sometimes accepted, on clinical indications, to be analyzed by an amplification method.
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Affiliation(s)
- W H F Goessens
- Erasmus MC, University Medical Center Rotterdam, Dept. of Medical Microbiology & Infectious Diseases, Dr. Molewaterplein 40, 3015 GD Rotterdam, The Netherlands.
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Abstract
Diagnostic testing for tuberculosis has remained unchanged for nearly a century, but newer technologies hold the promise of a true revolution in tuberculosis diagnostics. New tests may well supplant the tuberculin skin test in diagnosing latent tuberculosis infection in much of the world. Tests such as the nucleic acid amplification assays allow more rapid and accurate diagnosing of pulmonary and extrapulmonary tuberculosis. The appropriate and affordable use of any of these tests depends on the setting in which they are employed.
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Affiliation(s)
- Daniel Brodie
- Division of Pulmonary, Allergy, and Critical Care Medicine, Columbia University Medical Center, 622 West 168th Street, PH 8 East, Room 101, New York, NY 10032, USA
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Blanie M, Pellegrin JL, Maugein J. Apport de la PCR dans le diagnostic des tuberculoses extrapulmonaires. Med Mal Infect 2005; 35:17-22. [PMID: 15695028 DOI: 10.1016/j.medmal.2004.08.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2004] [Accepted: 08/23/2004] [Indexed: 11/22/2022]
Abstract
UNLABELLED Extrapulmonary tuberculosis is usually more difficult to diagnose than pulmonary tuberculosis. It often involves inaccessible sites and it is paucibacillary. OBJECTIVE AND METHOD In this study, we tried to analyze the performance of various bacteriological methods used to diagnose 51 cases of extrapulmonary tuberculosis in an infectious diseases ward. RESULTS AND COMMENTS The culture was positive for 55% of patients. The new amplification methods used were very disappointing for the testing of nonrespiratory samples. The sensitivity of PCR was 32% compared to that of diagnostic culture which remains the most sensitive reference method. Liquid media allow for rapid growth and limit the contaminations. The combined inoculation of liquid and solid medium increases the sensitivity and helps to identify the pathogen.
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Affiliation(s)
- M Blanie
- Service d'hygiène hospitalière, centre hospitalier Périgueux, 80, avenue Georges-Pompidou, 24019 Périgueux cedex, France.
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18
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Wang JY, Lee LN, Chou CS, Huang CY, Wang SK, Lai HC, Hsueh PR, Luh KT. Performance assessment of a nested-PCR assay (the RAPID BAP-MTB) and the BD ProbeTec ET system for detection of Mycobacterium tuberculosis in clinical specimens. J Clin Microbiol 2004; 42:4599-603. [PMID: 15472315 PMCID: PMC522346 DOI: 10.1128/jcm.42.10.4599-4603.2004] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The performance of a nested PCR-based assay (the RAPID BAP-MTB; AsiaGen, Taichung, Taiwan) and the BD ProbeTec ET (DTB) system (Becton Dickinson, Sparks, Md.) for detection of Mycobacterium tuberculosis was evaluated with 600 consecutive clinical samples. These samples, including 552 respiratory specimens and 48 nonrespiratory specimens, were collected from 333 patients treated at National Taiwan University Hospital from September to October 2003. The results of both assays were compared to the gold standard of combined culture results and clinical diagnosis. The overall sensitivity and specificity of the RAPID BAP-MTB assay for respiratory specimens were 66.7% and 97.2%, respectively, and for the DTB assay they were 56.7% and 95.3%, respectively. The positive and negative predictive values for the RAPID BAP-MTB were 74.1% and 96.0%, respectively, and for the DTB assay they were 59.6% and 94.7%, respectively. For smear-negative samples, the sensitivity of the RAPID BAP-MTB and DTB assays was 57.1% and 40.5%, respectively. The RAPID BAP-MTB assay produced 14 false-positive results in 14 samples, including one of the six samples yielding Mycobacterium abscessus, one of the six samples yielding Mycobacterium avium intracellulare, one sample from a patient with a history of pulmonary tuberculosis with complete treatment, and three samples from three patients with a previous diagnosis of tuberculosis who were under treatment at the time of specimen collection. Among the 48 nonrespiratory specimens, the RAPID BAP-MTB assay was positive in one biopsy sample from a patient with lumbar tuberculous spondylitis and one pus sample from a patient with tuberculous cervical lymphadenopathy. Our results showed that the RAPID BAP-MTB assay is better than the DTB assay for both respiratory specimens and nonrespiratory specimens. The overall time for processing this assay is only 5 h. In addition, its diagnostic accuracy in smear-negative samples is as high as in smear-positive samples.
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Affiliation(s)
- Jann-Yuan Wang
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
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19
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Lemaître N, Armand S, Vachée A, Capilliez O, Dumoulin C, Courcol RJ. Comparison of the real-time PCR method and the Gen-Probe amplified Mycobacterium tuberculosis direct test for detection of Mycobacterium tuberculosis in pulmonary and nonpulmonary specimens. J Clin Microbiol 2004; 42:4307-9. [PMID: 15365029 PMCID: PMC516309 DOI: 10.1128/jcm.42.9.4307-4309.2004] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Real-time PCR was compared to Amplified Mycobacterium tuberculosis Direct Test (AMTDII) for 100 clinical specimens. The overall sensitivities of the real-time PCR method and AMTDII were similar for respiratory and nonrespiratory specimens. However, real-time PCR seemed to be less susceptible to amplification inhibitors than AMTDII.
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Affiliation(s)
- Nadine Lemaître
- Laboratoire de Bactériologie-Hygiène, Centre Hospitalier Régional Universitaire de Lille, France.
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20
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Sloutsky A, Han LL, Werner BG. New method for detection of Mycobacterium tuberculosis Direct Test inhibitors in clinical specimens. Diagn Microbiol Infect Dis 2004; 50:109-11. [PMID: 15474319 DOI: 10.1016/j.diagmicrobio.2004.06.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2004] [Accepted: 06/17/2004] [Indexed: 11/18/2022]
Abstract
Existing protocols for the detection of Mycobacterium tuberculosis Direct Test (MDT) inhibitors require substantial quantities of specimen and cannot distinguish Mycobacterium tuberculosis complex from other mycobacteria if inhibitors are present. We describe a preliminary evaluation of a simple and practical protocol for MTD inhibitor testing that circumvents these difficulties.
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Affiliation(s)
- A Sloutsky
- Massachusetts State Laboratory Institute, Boston, MA 02130, USA.
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21
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Johansen IS, Lundgren B, Tabak F, Petrini B, Hosoglu S, Saltoglu N, Thomsen VØ. Improved sensitivity of nucleic acid amplification for rapid diagnosis of tuberculous meningitis. J Clin Microbiol 2004; 42:3036-40. [PMID: 15243056 PMCID: PMC446323 DOI: 10.1128/jcm.42.7.3036-3040.2004] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Early diagnosis of tuberculous meningitis (TBM) is essential for a positive outcome; but present microbiological diagnostic techniques are insensitive, slow, or laborious. We evaluated the standard BDProbeTec ET strand displacement amplification method (the standard ProbeTec method) for the detection of Mycobacterium tuberculosis complex organisms in parallel with the ProbeTec method with a modified pretreatment procedure with 101 prospectively collected cerebrospinal fluid specimens from 94 patients with suspected TBM. By the modified method, the sample-washing step was omitted. A definitive diagnosis was attained by culture. Thirteen specimens from 12 patients were culture positive for M. tuberculosis complex organisms; three specimens (23%) were microscopy positive for acid-fast bacilli. Among the culture-positive specimens, the standard ProbeTec method was positive for 8 (61.5%) and the modified assay was positive for 10 (76.9%). The overall specificity by both procedures was 98.8% compared to the results of culture. After discrepancy analysis, conducted by reviewing the patients' previous laboratory data, the specificity increased to 100%. If the cutoff value for respiratory specimens was adjusted from the recommended value of 3,400 to 1,000, the sensitivity of the modified procedure increased to 84.7%, with unchanged specificity. Results were obtained in 3 to 4 h. The new pretreatment procedure with the ProbeTec assay described here provides a rapid, simple, and sensitive tool for the diagnosis of TBM.
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Affiliation(s)
- Isik Somuncu Johansen
- International Reference Laboratory of Mycobacteriology, Statens Serum Institut, 5 Artillerivej, 2300 Copenhagen S, Denmark.
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22
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Sloutsky A, Han LL, Werner BG. Practical strategies for performance optimization of the enhanced gen-probe amplified mycobacterium tuberculosis direct test. J Clin Microbiol 2004; 42:1547-51. [PMID: 15071002 PMCID: PMC387570 DOI: 10.1128/jcm.42.4.1547-1551.2004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The enhanced Gen-Probe Amplified Mycobacterium Tuberculosis Direct (MTD) test was evaluated using a combined set of 338 acid-fast smear-positive and smear-negative, respiratory and nonrespiratory clinical specimens received by the Massachusetts State Tuberculosis Laboratory from September 1999 through March 2002. Microbiological culture was used as the reference method; therefore, the sensitivity and specificity of the MTD test were calculated for culture-positive specimens only. The initial assessment indicated that the overall sensitivity, specificity, and positive and negative predictive values of the MTD test for all specimens grouped together were 62, 98, 99, and 68%, respectively. A detailed discrepancy analysis revealed that two major factors causing negative MTD results in specimens that were culture positive for M. tuberculosis complex were patient treatment with antituberculosis drugs prior to testing and the presence of inhibitory substances in the specimen. Based on these findings, a protocol for optimizing MTD test performance in this setting is proposed in which (i) specimens from patients taking antituberculosis medications are excluded from testing and (ii) all initially MTD-negative or MTD-equivocal specimens are subjected to testing for inhibitors. If this strategy was followed, the MTD test sensitivity would be at least 91%, a significant improvement over the initial sensitivity of 62%. Accordingly, the negative predictive value would increase from 68 to 91%.
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Affiliation(s)
- A Sloutsky
- Massachusetts State Laboratory Institute, Boston, Massachusetts 02130, USA.
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23
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Kim SY, Park YJ, Kang SJ, Kim BK, Kang CS. Comparison of the BDProbeTec ET system with the roche COBAS AMPLICOR System for detection of Mycobacterium tuberculosis complex in the respiratory and pleural fluid specimens. Diagn Microbiol Infect Dis 2004; 49:13-8. [PMID: 15135494 DOI: 10.1016/j.diagmicrobio.2003.11.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2003] [Accepted: 11/20/2003] [Indexed: 02/07/2023]
Abstract
The new BDProbeTec ET System (BDET; BD Biosciences, Sparks, MD) was compared with the Roche COBAS AMPLICOR System (CAS) and culture for Mycobacterium tuberculosis (MTB). A total of 253 specimens (152 respiratory and 101 pleural fluid specimens) collected from 240 patients were tested in parallel with the 3 assays. After resolving the discrepancies, the sensitivity, specificity, and positive and negative predictive values of the BDET for detecting MTB was 76.9%, 93.7%, 71.4%, and 95.2% for the respiratory specimens and 88.9%, 92.4%, 53.3%, and 98.8% for the pleural fluid specimens, respectively. The corresponding values of the CAS were 69.2%, 100%, 100%, and 94% for the respiratory specimens and 33.3%, 100%, 100%, and 93.9% for the pleural fluid specimens, respectively. No significant differences in sensitivities were observed between the results of both assays for the respiratory specimens. However, statistically significant differences in sensitivities were found between the BDET and CAS for the pleural fluid specimens (P =.02). Although the BDET was less specific than the CAS (P =.007), the BDET has an excellent sensitivity for detecting MTB in the pleural fluid specimens. Considering the low sensitivity of other available tests, the BDET can be a useful diagnostic tool for excluding MTB, particularly in the pleural fluid specimens.
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Affiliation(s)
- Soo-Young Kim
- Department of Clinical Pathology, College of Medicine, the Catholic University of Korea, St. Vincent's Hospital, Suwon, South Korea
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24
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Piersimoni C, Scarparo C. Relevance of commercial amplification methods for direct detection of Mycobacterium tuberculosis complex in clinical samples. J Clin Microbiol 2004; 41:5355-65. [PMID: 14662911 PMCID: PMC309028 DOI: 10.1128/jcm.41.12.5355-5365.2003] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Claudio Piersimoni
- Department of Clinical Microbiology, General Hospital Umberto I, Ancona, Italy.
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25
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Jesús de la Calle I, Jesús de la Calle MA, Rodríguez-Iglesias M. Evaluation of the BDProbeTec ET system as screening tool in the direct detection of mycobacterium tuberculosis complex in respiratory specimens. Diagn Microbiol Infect Dis 2004; 47:573-8. [PMID: 14711478 DOI: 10.1016/s0732-8893(03)00163-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
We evaluated the BDProbeTec ET System (Becton Dickinson) for the routine detection of Mycobacterium tuberculosis complex (MTC) in respiratory specimens and pleural fluids, comparing with microscopy (Ziehl Neelsen stain, ZN) and culture in liquid (BACTEC MGIT 960, MGIT) and solid (Löwenstein Jensen, LJ) media. Five hundred and two specimens, collected from 266 patients, of which 257 with suspected tuberculosis and 9 receiving anti-tuberculosis treatment, were investigated. Thirty-nine specimens were positive by any method, including false positives. Mycobacteria were isolated from 33 specimens (32 Mycobacterium tuberculosis and 1 Mycobacterium chelonae). Thirty-six specimens were BDProbeTec ET positive, 33 specimens were MGIT positive, 27 were LJ positive and 22 were ZN positive. With BDProbeTec ET, 2 specimens were false negative (culture positive), and 2 specimens from non-treated patients were false positive (culture negative). The overall sensitivity, specificity, and positive and negative predictive values for BDProbeTec ET compared to culture were 93.7, 98.7, 83.3, and 99.5%, respectively, while with smear-positive and smear-negative specimens the sensitivities were 100% and 81.5% respectively. In five treated patients the disappearance of MTC could be monitored using BDProbeTec ET in parallel with culture. The overall inhibition rate was 0.2%. BDProbeTec ET can be very useful for rapid detection of MTC, especially in smear-negative respiratory specimens.
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Affiliation(s)
- Iría Jesús de la Calle
- Laboratory of Microbiology, Puerto Real University Hospital, University of Cádiz, Cadiz, Spain
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26
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27
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The Use of Molecular Methods to Determine the Cause of Mycobacterial Infections. PATHOLOGY CASE REVIEWS 2003. [DOI: 10.1097/01.pcr.0000076495.47026.5b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Abstract
In developing countries, many sputum-negative suspects of pulmonary tuberculosis (PTB) are given antituberculous medication just because tuberculosis (TB) could not be excluded in them. Many studies have shown that BCG test is nearly 100% sensitive, except in those with severe malnutrition, steroid therapy and other causes of immunosuppression. The aim of the present study was to find out the proportion of PTB suspects in whom BCG test may be useful in excluding diagnosis of TB. The study was carried out on adult subjects attending District Tuberculosis Clinic (DTC), Pali, Rajasthan, India. Out of 104 subjects studied, all 18 sputum-positive subjects showed a positive BCG test indicating 100% sensitivity of the test. The result of BCG test was negative in 16.28% of 86 sputum-negative suspects of TB. The BCG test did not show any adverse reactions among these cases except for adenitis of axillary or cervical lymph nodes in 6.7% subjects. The study raises the possibility that BCG test may be useful in excluding diagnosis of tuberculosis in a proportion of adult sputum negative-suspects of PTB in developing countries like India. More studies are needed in this direction.
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Affiliation(s)
- M L Mathur
- Desert Medicine Research Centre, New Pali Road, Jodhpur, India.
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29
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Mazzarelli G, Rindi L, Piccoli P, Scarparo C, Garzelli C, Tortoli E. Evaluation of the BDProbeTec ET system for direct detection of Mycobacterium tuberculosis in pulmonary and extrapulmonary samples: a multicenter study. J Clin Microbiol 2003; 41:1779-82. [PMID: 12682186 PMCID: PMC153925 DOI: 10.1128/jcm.41.4.1779-1782.2003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We evaluated the BDProbeTec ET system (Becton Dickinson, Sparks, Md.), a strand displacement amplification-based technique, for direct detection of Mycobacterium tuberculosis in 867 clinical samples. Of 294 extrapulmonary specimens, 52 had positive results by both BDProbeTec ET and culture and 209 had negative results by both methods; sensitivity and specificity were 76.5 and 95.9%, respectively. After resolution of discrepancies, the sensitivity rose to 77.8%.
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Affiliation(s)
- Gianna Mazzarelli
- Microbiology and Virology Laboratory, Regional Reference Center for Mycobacteria, Careggi Hospital, Florence, Italy
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30
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Drobniewski FA, Caws M, Gibson A, Young D. Modern laboratory diagnosis of tuberculosis. THE LANCET. INFECTIOUS DISEASES 2003; 3:141-7. [PMID: 12614730 DOI: 10.1016/s1473-3099(03)00544-9] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
One-third of the global population is believed to be infected with bacteria of the Mycobacterium tuberculosis complex, the causative agent of tuberculosis. More than 8 million new cases of tuberculosis occur annually leading to 2 million deaths. Mortality is particularly high in those coinfected with HIV and where the bacteria are multiple-drug-resistant strains--ie, strains resistant to at least isoniazid and rifampicin. Early diagnosis of tuberculosis and drug resistance improves survival and by identifying infectious cases promotes contact tracing, implementation of institutional cross-infection procedures, and other public-health actions. This review addresses significant advances made in the diagnosis of infection, clinical disease, and drug resistance over the past decade. It proposes operational criteria for a modern diagnostic service in the UK (as a model of a low-incidence country) and explores some of the economic issues surrounding the use of these techniques.
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Affiliation(s)
- F A Drobniewski
- PHLS Mycobacterium Reference Unit and Department of Infection, Guy's King's and St Thomas' Medical College, King's College Hospital (Dulwich) London, UK.
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31
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Dowdy DW, Maters A, Parrish N, Beyrer C, Dorman SE. Cost-effectiveness analysis of the gen-probe amplified mycobacterium tuberculosis direct test as used routinely on smear-positive respiratory specimens. J Clin Microbiol 2003; 41:948-53. [PMID: 12624014 PMCID: PMC150318 DOI: 10.1128/jcm.41.3.948-953.2003] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A decision analysis was conducted to evaluate the cost-effectiveness of programs in which the Amplified Mycobacterium Tuberculosis Direct test (MTD) (Gen-Probe) is used to rapidly exclude Mycobacterium tuberculosis complex as a cause of disease in smear-positive respiratory specimens. MTD sensitivity, specificity, and probability of inhibition for smear-positive specimens were estimated from literature reports. Costs and laboratory performance characteristics were determined from review of records and practices at an urban hospital in the mid-Atlantic United States. In the base case, 31.4% of smear-positive specimens were assumed to be culture positive for M. tuberculosis. Under these conditions, the marginal cost of the MTD testing program was estimated as $338 per smear-positive patient, or $494 per early exclusion of tuberculosis based on negative MTD results. By comparison, the cost of respiratory isolation ($27.77/day) and drugs ($5.66/day) averted by MTD testing was estimated at $201 per early tuberculosis exclusion. MTD testing was therefore not cost-effective in this scenario. Sensitivity analysis revealed that cost-effectiveness estimates are sensitive to the number of smear-positive specimens processed annually, the relative prevalence of M. tuberculosis in smear-positive specimens, and the marginal daily cost of respiratory isolation. A decision tool is therefore presented for assessing the cost-effectiveness of MTD under various combinations of those three variables. While routine MTD testing of smear-positive specimens is not expected to be cost-saving for most individual hospitals, centralized reference laboratories may be able to implement MTD in a cost-effective manner across a wide range of situations.
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Affiliation(s)
- David W Dowdy
- Johns Hopkins Bloomberg School of Public Health. Johns Hopkins Hospital. Johns Hopkins University School of Medicine, Baltimore, Maryland 21231, USA.
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32
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Funatsu T, Taniyama T, Tajima T, Tadakuma H, Namiki H. Rapid and sensitive detection method of a bacterium by using a GFP reporter phage. Microbiol Immunol 2003; 46:365-9. [PMID: 12153113 DOI: 10.1111/j.1348-0421.2002.tb02708.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A rapid, sensitive, and convenient method for detecting a specific bacterium was developed by using a GFP phage. Here we describe a model system that utilizes the temperate Escherichia coli-restricted bacteriophage lambda, which was genetically modified to express a reporter gene for GFP to identify the colon bacillus E. coli in the specimen. E. coli infected with GFP phage was detected by GFP fluorescence after 4-6 hr of incubation. The results show that a few bacteria in a specimen can be detected under fluorescence microscopy equipped with a sensitive cooled CCD camera. When E. coli and Mycobacterium smegmatis were mixed in a solution containing GFP phage, only E. coli was infected, indicating the specificity of this method. The method has the following advantages: 1) Bacteria from biological samples need not be purified unless they contain fluorescent impurities; 2) The infection of GFP phage to bacteria is specific; 3) The fluorescence of GFP within infected bacteria enables highly sensitive detection; 4) Exogenous substrates and cofactors are not required for fluorescence. Therefore this method is suitable for any phage-bacterium system when bacteria-specific phages are available.
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Affiliation(s)
- Takashi Funatsu
- Department of Physics, School of Science and Engineering, Waseda University, Tokyo, Japan.
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Montenegro SH, Gilman RH, Sheen P, Cama R, Caviedes L, Hopper T, Chambers R, Oberhelman RA. Improved detection of Mycobacterium tuberculosis in Peruvian children by use of a heminested IS6110 polymerase chain reaction assay. Clin Infect Dis 2003; 36:16-23. [PMID: 12491196 DOI: 10.1086/344900] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2002] [Accepted: 09/12/2002] [Indexed: 11/04/2022] Open
Abstract
A novel heminested IS6110 polymerase chain reaction (PCR) assay was evaluated as a tool for diagnosing tuberculosis in 222 children. In an analysis of 392 specimens (gastric aspirates, nasopharyngeal aspirates, and sputum samples), results of PCR were compared with those of 3 culture methods, acid-fast bacillus (AFB) staining, and clinical assessment by the Stegen-Toledo score. The sensitivity of PCR (67%) was comparable to that of the 3-culture method (71%) and was significantly higher than that of Löwenstein-Jensen culture (54%) or AFB stain (42%) for children with highly probable tuberculosis. PCR detection rates for culture-positive specimens were 100% for smear-positive samples and 76.7% for smear-negative samples. The specificity of PCR was 100% in control children. Compared with culture, PCR demonstrated a sensitivity of 90.4%, a positive predictive value of 89%, a specificity of 94%, and a negative predictive value of 95% (kappa=.85). With clinical assessment as the standard, PCR had a sensitivity of 71%, a positive predictive value of 92%, a specificity of 95%, and a negative predictive value of 79% (kappa=.67). PCR is a rapid and sensitive method for the early diagnosis of pediatric tuberculosis.
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Affiliation(s)
- Sonia H Montenegro
- Molecular Immunogenetics Laboratory, Div. of Research, Ochsner Clinic Foundation, New Orleans, LA 70121, USA.
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Maugein J, Fourche J, Vacher S, Grimond C, Bebear C. Evaluation of the BDProbeTec ET DTB assay(1) for direct detection of Mycobacterium tuberculosis complex from clinical samples. Diagn Microbiol Infect Dis 2002; 44:151-5. [PMID: 12458121 DOI: 10.1016/s0732-8893(02)00427-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The purpose of this study was to evaluate the ability of BDProbeTec ET DTB system to detect Mycobacterium tuberculosis complex directly from clinical specimens. A total of 628 specimens (553 respiratory and 75 non respiratory specimens) were collected from 478 patients. These samples were tested with the BDProbeTec ET DTB assay and results were compared with acid fast microscopy and culture. Sixty eight out of 77 culture positive M. tuberculosis complex samples were detected with overall sensitivity and specificity of 89.5% and 98.2% respectively. Overall sensitivity was 100% in smear positive samples and 79% in smear negative samples. After resolution of discrepant results, sensitivity and specificity for respiratory samples were 91.6% and 98.7% respectively. BDProbeTec ET DTB assay demonstrated to be a rapid, sensitive and specific method for detection of M. tuberculosis complex.
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Affiliation(s)
- J Maugein
- Laboratoire de Bactériologie, Hôpital Haut-Levêque, 33604, Pessac Cedex, France.
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35
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O'Sullivan CE, Miller DR, Schneider PS, Roberts GD. Evaluation of Gen-Probe amplified mycobacterium tuberculosis direct test by using respiratory and nonrespiratory specimens in a tertiary care center laboratory. J Clin Microbiol 2002; 40:1723-7. [PMID: 11980950 PMCID: PMC130650 DOI: 10.1128/jcm.40.5.1723-1727.2002] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The performance of the Amplified Mycobacterium Tuberculosis Direct (AMTD) test (Gen-Probe Inc., San Diego, Calif.) was assessed in a large tertiary care mycobacteriology laboratory. Both acid-fast smear-positive and smear-negative respiratory and nonrespiratory clinical specimens were analyzed. From February 1998 to 4 October 2001, AMTD assays were performed on 391 respiratory specimens and 164 nonrespiratory specimens. The AMTD assay was compared to the "gold standard" of combined culture and clinical diagnosis. The overall sensitivity for all specimens, including those for which no smear result was available, was 91.2%. The overall sensitivities of the assay, including acid-fast smear-positive and -negative specimens, were 97.8 and 77.3% for respiratory and nonrespiratory specimens, respectively. The corresponding specificities for respiratory and nonrespiratory specimens were 99.1 and 98.5%, respectively. The overall specificity for all specimens was 98.9%. Positive and negative predictive values were 93.9 and 99.7% and 91.7 and 96.4% for respiratory and nonrespiratory specimens, respectively. The time saved by using the AMTD test for making a diagnosis of tuberculosis instead of using culture was 8.99 days. Inhibitors to the AMTD assay were found in 3.1% of respiratory specimens and 3.1% of nonrespiratory specimens. The assay, used in a general mycobacteriology laboratory setting, represents an important advance in improving the speed and accuracy of diagnosis in the management of patients with tuberculosis.
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Affiliation(s)
- Cathal E O'Sullivan
- Immunocompromised Host Section, Pediatric Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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36
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Abstract
Use of the most rapid and reliable laboratory tests for mycobacterial detection, identification, and susceptibility testing is important for TB control. In 1993, CDC experts made recommendations regarding optimal methods of mycobacterial testing (i.e., stains for AFB, culture, identification, and susceptibility testing of M. tuberculosis) and turnaround times for reporting results. Various technical advances have enhanced the diagnostic capability of the laboratory and/or improved laboratory efficiency since then. The commercial NAA tests for direct detection of MTBC have the greatest potential to impact patient care. To assist physicians, CDC experts have published recommendations concerning use of the NAA tests for management of patients with suspected TB, with emphasis on the MTD assay, which is approved for both AFB smear-positive and smear-negative specimens. With regard to mycobacterial culture, totally automated, nonradiometric systems are commercially available. For mycobacterial identification, various molecular techniques have been developed, but at present, they are used predominantly in research or large reference laboratories. Molecular tests also have proved useful for better understanding the epidemiology of TB and investigating episodes of suspected laboratory cross-contamination. With regard to mycobacterial susceptibility testing, use of the new automated culture systems for testing MTBC is under evaluation, but only one such system has been approved for this purpose. In addition, laboratory guidelines for susceptibility testing of MTBC and certain NTM have recently been published by the NCCLS.
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Affiliation(s)
- Gail L Woods
- Department of Medical Communications, Infectious Diseases, Merck & Co., Inc., Blue Bell, Pennsylvania, USA.
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Valente C, Cuteri V, Ausili E, Piersimoni C. Evaluation of the Abbott LCx Mycobacterium tuberculosis assay for direct detection of Mycobacterium bovis in bovine tissue samples. Vet Res Commun 2002; 26:21-7. [PMID: 11860084 DOI: 10.1023/a:1013349504066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The commercial LCx amplification assay, usually employed to detect the Mycobacterium tuberculosis complex in respiratory specimens, was evaluated by comparing the results it gave with those obtained using Lowenstein-Jensen solid medium and pathological findings in 55 lymph nodes from cattle with positive and 10 lymph nodes from cattle with negative skin tests for tuberculosis. Fifty-three cultures (51 and 2, respectively) were positive for M. bovis, while the results for the LCx assay and the histological method were positive in 48 (45, 3) and 24 (20, 4) samples, respectively. None of the samples from cattle from certified tuberculosis-free herds were positive by any of the procedures. The results obtained with the LCx assay, compared with the culture procedure, regarded as the gold standard among the diagnostic techniques, gave a specificity of 91.6% and sensitivity of 90.5%. Although the sensitivity of LCx was suboptimal, DNA of M. bovis was detected in 81.8% of the skin test-positive animals. Amplification techniques could provide a rapid and reasonably reliable tool for detecting bovine tuberculosis.
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Affiliation(s)
- C Valente
- Infectious Diseases, School of Veterinary Medicine, University of Perugia, Italy.
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Affiliation(s)
- N W Schluger
- Division of Pulmonary, Allergy, and Critical Care Medicine, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
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Caws M, Drobniewski FA. Molecular techniques in the diagnosis of Mycobacterium tuberculosis and the detection of drug resistance. Ann N Y Acad Sci 2001; 953:138-45. [PMID: 11795406 DOI: 10.1111/j.1749-6632.2001.tb11371.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Early diagnosis of Mycobacterium tuberculosis disease is crucial in initiating treatment and interrupting the train of transmission. The increasing incidence of MDR TB worldwide has also placed emphasis on the need for early detection of drug resistance, particularly to isoniazid and rifampicin. Molecular diagnostic techniques and automated culture systems have reduced turnaround times in the modern mycobacteriology laboratory, and the continuing evaluation and development of such techniques is increasing the use of molecular technology in developed nations. Simple phenotypic methods for the detection of resistance to first-line drugs and genotypic kit-form assays for detection of rifampicin resistance have been developed that have become key tools in the containment of MDR TB.
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Affiliation(s)
- M Caws
- PHLS Mycobacterium Reference Unit, Guy's, King's and St Thomas' School of Medicine, King's College Hospital (Dulwich), London, UK.
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Alcalá L, Ruiz-Serrano MJ, Hernangómez S, Marín M, García de Viedma D, San Juan R, Bouza E. Evaluation of the upgraded amplified Mycobacterium tuberculosis direct test (gen-probe) for direct detection of Mycobacterium tuberculosis in respiratory and non-respiratory specimens. Diagn Microbiol Infect Dis 2001; 41:51-6. [PMID: 11687314 DOI: 10.1016/s0732-8893(01)00279-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We evaluated the upgraded Amplified Mycobacterium Tuberculosis Direct Test kit (AMTD) (Gen-Probe Inc.) for the direct detection of Mycobacterium tuberculosis in respiratory and non-respiratory specimens, and compared the results between the traditional 30,000 RLUs cutoff criteria (C) and three equivocal ranges (30,000-100,000, R1; 30,000-500,000, R2; and 30,000-1,000,000, R3). We tested 663 respiratory and 238 non-respiratory samples from 464 patients. The gold standard was considered to be the combination of culture and clinical data. One hundred and nineteen samples were from 56 patients with pulmonary tuberculosis, and 36 samples were from 19 patients with extrapulmonary tuberculosis. When C criteria was applied, the sensitivity and specificity values were 90.8 and 93.0% for respiratory specimens, while they were 88.9 and 92.1% for non-respiratory specimens (p = NS). The sensitivity was significantly higher in smear-positive specimens (96.7%) than in smear-negative ones (81.0%) (p < 0.05). When compared with C criteria, the overall sensitivity was maintained at 90.3% for R1 criteria, and slightly decreased to 89.7% for R2 and R3 criteria (p = NS). Overall, specificity increased significantly from 92.9% (C) to 97.5% (R1), 99.1% (R2), and 99.2% (R3). Application of R2 or R3 criteria improved significantly the specificity of the test with little decrease in sensitivity.
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Affiliation(s)
- L Alcalá
- Servicio de Microbiología y Enfermedades Infecciosas/VIH, Hospital General Universitario Gregorio Marañón Dr. Esquerdo, 46, 28009, Madrid, Spain.
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Woods GL, Bergmann JS, Williams-Bouyer N. Clinical Evaluation of the Gen-Probe amplified mycobacterium tuberculosis direct test for rapid detection of Mycobacterium tuberculosis in select nonrespiratory specimens. J Clin Microbiol 2001; 39:747-9. [PMID: 11158142 PMCID: PMC87811 DOI: 10.1128/jcm.39.2.747-749.2001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The performance of the Amplified Mycobacterium Tuberculosis Direct Test (MTD; Gen-Probe, Inc., San Diego, Calif.) for rapid diagnosis of extrapulmonary tuberculosis was evaluated by testing 178 nonrespiratory specimens from 158 patients. Criteria for specimen inclusion were (i) a positive smear for acid-fast bacilli (n = 54) and (ii) the source if the smear was negative (tissue biopsies and aspirates and abscess material were tested; n = 124). Results were compared to those of mycobacterial culture; clinical history was reviewed when MTD and culture results disagreed. Forty-eight specimens (27.0%) were positive for mycobacteria, including 23 Mycobacterium tuberculosis complex specimens; of which 21 were smear positive. Twenty-five specimens were MTD positive; 20 of these grew M. tuberculosis complex. All of the five MTD-positive, M. tuberculosis complex culture-negative specimens were considered truly positive, based on review of the medical record. Of the three MTD-negative, M. tuberculosis complex culture-positive specimens, two contained inhibitory substances; one of the two was smear positive. Excluding the latter specimen from analysis, after chart review, the sensitivity, specificity, and positive and negative predictive values of the MTD were 92.6, 100, 100, and 98.7%, respectively, by specimen and 89.5, 100, 100, and 98.6% by patient. Given the few smear-negative samples from patients with extrapulmonary tuberculosis in our study, additional similar studies that include more smear-negative, M. tuberculosis complex culture-positive specimens to confirm our data are desirable.
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Affiliation(s)
- G L Woods
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas 77555-0740, USA.
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Rantakokko-Jalava K, Marjamäki M, Marttila H, Mäkelä L, Valtonen V, Viljanen MK. LCx Mycobacterium tuberculosis assay is valuable with respiratory specimens, but provides little help in the diagnosis of extrapulmonary tuberculosis. Ann Med 2001; 33:55-62. [PMID: 11310940 DOI: 10.3109/07853890109002060] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Commercial nucleic acid amplification tests, designed for the detection of Mycobacterium tuberculosis DNA/RNA in respiratory samples, are often applied also in nonrespiratory specimens in order to verify the diagnosis of extrapulmonary tuberculosis. AIM. To evaluate the value of the Abbott LCx Mycobacterium tuberculosis assay for the diagnosis of pulmonary and extrapulmonary tuberculosis based on routine clinical laboratory results. METHODS The assay was used to analyse 350 respiratory and 826 nonrespiratory specimens from 961 patients, of whom 3.6% had culture-proven tuberculosis. The results obtained by the LCx assay were compared with the records on mycobacterial isolates of the national reference laboratory and, in the case of positive findings, with clinical data. RESULTS In comparison with culture, the sensitivity, specificity and positive/negative predictive value of the assay on respiratory specimens were 87.5%, 99.7%, 93.3% and 99.4%, respectively. With nonrespiratory specimens, the overall sensitivity, specificity and positive/negative predictive value of the LCx assay were 73.3%, 98.0%, 40.7% and 99.5%, respectively. When clinical and histological data were also included, the positive predictive value of LCx with nonrespiratory specimens was 45.8%. CONCLUSION Critical interpretation of the nucleic acid amplification results obtained from nonrespiratory specimens is necessary in both laboratory and clinical settings.
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Abstract
OBJECTIVE To assess the clinical utility of the commercial nucleic acid amplification (NAA) tests (ie, Amplified Mycobacterium Tuberculosis Direct Test, Gen-Probe, Inc and AMPLICOR Mycobacterium tuberculosis Test, Roche Molecular Systems, Inc) for direct detection of Mycobacterium tuberculosis complex. DATA SOURCES Review of the English-language literature. CONCLUSIONS The performance of both NAA tests is excellent (sensitivity, > or = 95%; specificity, 100%) when testing respiratory specimens that are smear-positive for acid-fast bacilli (AFB). Only the Gen-Probe assay is approved for testing respiratory specimens regardless of the AFB smear result. Data from 3 studies showed that the sensitivity of the Mycobacterium Tuberculosis Direct Test in smear-negative patients ranged from 83% to 85%, and that the specificity was 99%. Both NAA tests have been used to test nonrespiratory specimens; in some studies, the performance was comparable to the performance obtained for respiratory specimens, whereas in others, it was lower. The NAA tests also appear to be reliable tools for rapid detection of M tuberculosis complex in positive broth cultures of all specimen types (except blood). The impact of the NAA tests on patient outcome varies based on the result of the AFB smear. In smear-positive patients, public health and hospital infection-control resources are predominantly affected. The potential for influencing patient outcome is much greater when the AFB smear is negative. In smear-negative patients, the NAA test could provide more rapid diagnosis of tuberculosis and subsequent initiation of therapy; eliminate the need for invasive diagnostic procedures, which are both costly and pose an added risk to the patient; and allow earlier discharge of hospitalized patients. Prospective studies concerning the cost-effectiveness of the NAA tests are needed.
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Affiliation(s)
- G L Woods
- Department of Pathology, University of Texas Medical Branch-Galveston, Galveston, Tex 77555-0740, USA.
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Abstract
This review summarises recent advances made in microscopic techniques (fluorescence and peptide nucleic acids) and culture techniques (solid, liquid, radiometric, and non-radiometric systems) and in the development of rapid methods for the identification of mycobacterial cultures (high performance liquid chromatography, thin layer chromatography, RNA sequencing, and polymerase chain reaction restriction enzyme assays). The role of molecular amplification systems in identifying Mycobacterium tuberculosis is described. Most methods record high specificity and sensitivity for smear positive sputum but have variable sensitivity for sputum smear negative and extrapulmonary specimens. Specimen quality will affect the performance of these assays and organisational delays, such as the batching of specimens, can reduce the time saved. In house assays can be as effective as commercial systems as long as appropriate controls are used.
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Affiliation(s)
- S A Watterson
- Public Health Laboratory Service, Dulwich Public Health Laboratory, Guy's, King's and St Thomas's School of Medicine, King's College Hospital, London, UK
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Lim TK, Gough A, Chin NK, Kumarasinghe G. Relationship between estimated pretest probability and accuracy of automated Mycobacterium tuberculosis assay in smear-negative pulmonary tuberculosis. Chest 2000; 118:641-7. [PMID: 10988184 DOI: 10.1378/chest.118.3.641] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
BACKGROUND The AMPLICOR assay (Roche; Branchburg, NJ), a rapid direct amplification test for Mycobacterium tuberculosis, has only been licensed for use in smear-positive respiratory specimens. However, many patients with pulmonary tuberculosis (PTB) have smear-negative disease. The clinical utility of this test in patients with smear-negative PTB is unknown. OBJECTIVE To evaluate the effect of pretest probability of PTB estimated by chest physicians on the accuracy of the AMPLICOR assay in patients with smear-negative PTB. DESIGN AND METHODS A prospective study of consecutive patients suspected of having smear-negative PTB. Two chest physicians estimated the pretest probability of active disease (high, intermediate, and low categories). Respiratory specimens were examined with radiometric broth medium cultures and with the AMPLICOR assay for M tuberculosis. The decision on a final diagnosis of PTB was blinded to the AMPLICOR results. RESULTS Active PTB was diagnosed in 25 of 441 patients (5.7%). The AMPLICOR assay had an overall sensitivity of 44% and a specificity of 99%. Results of the assay were negative in seven patients with culture-negative PTB. The proportions of patients in the high, intermediate, and low pretest groups were 4.5%, 19.7%, and 75.7%, respectively. The incidence of PTB for each group was 95%, 3.4%, and 0.9%, respectively. The sensitivities of the AMPLICOR assay in the three groups of patients were 47%, 33%, and 33%, respectively, while the specificities were 100%, 98%, and 99%, respectively. CONCLUSIONS In patients suspected of having smear-negative PTB, the following conclusions were drawn: (1) the incidence of active PTB was low; (2) pretest estimates accurately discriminated between patients with high and low risk of PTB; (3) the risk of PTB was overestimated in the intermediate group; and (4) the utility of the AMPLICOR assay in the intermediate-risk group may be limited by the overestimation of disease prevalence and low test sensitivity. Further studies are needed on the role of the AMPLICOR assay in better selected patients with an intermediate risk of having smear-negative PTB.
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Affiliation(s)
- T K Lim
- Department of Medicine, National University Hospital, Lower Kent Ridge Road, Singapore.
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Viinanen AH, Soini H, Marjamäki M, Liippo K, Viljanen MK. Ligase chain reaction assay is clinically useful in the discrimination of smear-positive pulmonary tuberculosis from atypical mycobacterioses. Ann Med 2000; 32:279-83. [PMID: 10852145 DOI: 10.3109/07853890009011773] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We evaluated the usefulness of the ligase chain reaction (LCR) (Abbott LCx Mycobacterium tuberculosis assay) during the initial diagnosis of tuberculosis. LCx was carried out in parallel with conventional methods for the analysis of clinical samples. Out of 86 patients who were examined clinically, 53 were suspected of having pulmonary tuberculosis, eight had residual X-ray scars from previous tuberculosis and 25 served as asymptomatic controls. Ten bronchoscopy samples and 237 sputum samples were analysed by direct microscopy, culture and LCx. All 11 smear-positive and two of three smear-negative tuberculosis patients had at least one LCx-positive specimen. All samples that were both LCx- and smear-positive were culture-positive for M. tuberculosis. The smear-positive samples from the five patients with atypical mycobacteriosis were LCx-negative. There were three false-positive results: one in a smear-negative sample from a patient with M. malmoense infection and two from two pneumonia patients. All samples from controls and patients with previous tuberculosis were LCx-negative. The sensitivity, specificity and the positive and negative predictive values of LCx in patient analysis were 92.9%, 95.8%, 81.3% and 98.6%, respectively. LCx assay of M. tuberculosis is useful in rapid confirmation of tuberculosis or atypical mycobacteriosis from a smear-positive sample and may aid in diagnosing smear-negative tuberculosis.
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Affiliation(s)
- A H Viinanen
- Turku University Central Hospital, Department of Pulmonary Diseases, Preitilä, Finland
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47
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Lumb R, Davies K, Dawson D, Gibb R, Gottlieb T, Kershaw C, Kociuba K, Nimmo G, Sangster N, Worthington M, Bastian I. Multicenter evaluation of the Abbott LCx Mycobacterium tuberculosis ligase chain reaction assay. J Clin Microbiol 1999; 37:3102-7. [PMID: 10488161 PMCID: PMC85503 DOI: 10.1128/jcm.37.10.3102-3107.1999] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Four Australian hospital laboratories evaluated the performance of the Abbott LCx Mycobacterium tuberculosis assay with 2,347 specimens (2,083 respiratory and 264 nonrespiratory specimens) obtained from 1, 411 patients. A total of 152 specimens (6.5%) were culture positive for Mycobacterium tuberculosis complex (MTBC); of these, 79 (52%) were smear positive. After resolution of discrepant data, the overall sensitivity, specificity, and positive and negative predictive values for the LCx assay were 69.7, 99.9, 99.1, and 97.7% respectively. For smear-positive respiratory specimens that were culture positive for MTBC, the values were 98.5, 100, 100, and 98.4%, respectively, while the values for smear-negative respiratory specimens were 41.5, 99.9, 96.4, and 98%, respectively. Relative operating characteristic curves were constructed to demonstrate the relationship between sensitivity and specificity for a range of possible cutoff values in the LCx assay. These graphs suggested that the assay sensitivity for respiratory samples could be increased from 70.2 to 78.6%, while the specificity would be reduced from 99.9 to 99.4% by inclusion of a grey zone (i.e., LCx assay values of between 0.2 and 0.99). An algorithm is presented for the handling of specimens with LCx assay values within this grey zone.
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Affiliation(s)
- R Lumb
- Infectious Diseases Laboratories, Institute of Medical and Veterinary Science, Adelaide, South Australia, Australia.
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Dawson DJ. Comparison of nucleic acid amplification tests for tuberculosis. J Clin Microbiol 1999; 37:1236. [PMID: 10215457 PMCID: PMC88689 DOI: 10.1128/jcm.37.4.1236-1236.1999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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