Use of the Amplified Mycobacterium tuberculosis Direct Test in a Public Health Laboratory

Guerra, Renata Leborato; Hooper, Nancy; Baker, James F.; Alborz, Roya; Armstrong, Derek T; Maltas, Gina; Kiehlbauch, Julia A.; Dorman, Susan E.

doi:10.1378/chest.06-2959

Cited by 50 publications

(37 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The more limited gain in likelihood of pulmonary TB after a positive result seems to reduce its application as a confirmatory test in these cases. This is particularly relevant, since the "clinical suspicion," when analyzed as a diagnostic test for TB, demonstrates a low positive predictive value, as well (26). The tendency of both clinical suspicion and hPCR to overestimate the probability of pulmonary TB might lead to erroneous initiation of therapy, isolation, and contact investigation.…”

Section: Discussionmentioning

confidence: 99%

Diagnostic Accuracy of In-House PCR for Pulmonary Tuberculosis in Smear-Positive Patients: Meta-Analysis and Metaregression

et al. 2009

View full text Add to dashboard Cite

In-house PCR (hPCR) could speed differential diagnosis between tuberculosis (TB) and nontuberculous mycobacterial disease in patients with positive smears and pulmonary infiltrates, but its reported accuracy fluctuates across studies. We conducted a systematic review and meta-analysis of hPCR sensitivity and specificity for smear-positive TB diagnosis, using culture as the reference standard. After searching English language studies in MEDLINE and EMBASE, we estimated cumulative accuracy by means of summary receiver operating characteristic analysis. The possible influence of hPCR procedures and study methodological features on accuracy was explored by univariate metaregression, followed by multivariate adjustment of items selected as significant. Thirty-five articles (1991 to 2006) met the inclusion criteria. The pooled estimates of the diagnostic odds ratio, sensitivity, and specificity (random-effect model) were, respectively, 60 (confidence interval [CI], 29 to 123), 0.96 (CI, 0.95 to 0.97), and 0.81 (CI, 0.78 to 0.84), but significant variations (mainly in specificity) limit their clinical applicability. The quality of the reference test, the detection method, and real-time PCR use explained some of the observed heterogeneity. Probably due to the limited study power of our meta-analysis and to the wide differences in both laboratory techniques and methodological quality, only real-time PCR also displayed a positive impact on accuracy in the multivariate model. Currently, hPCR can be confidently used to exclude TB in smear-positive patients, but its low specificity could lead to erroneous initiation of therapy, isolation, and contact investigation. As the inclusion of samples from treated patients could have artificially reduced specificity, future studies should report mycobacterial-culture results for each TB and non-TB sample analyzed.With the continuing expansion of human immunodeficiency virus and other immunosuppressive conditions, tuberculosis (TB), as well as infections caused by nontuberculous mycobacteria (NTM), have increased in many parts of the world. In addition, the spread of tumor necrosis factor alpha-blocking agents has led to high rates of development of both infections among patients affected by inflammatory and autoimmune diseases. Similarities in clinical and radiographic features, particularly in cases of fibrocavitary disease, make differential diagnosis between TB and NTM infection a difficult task. In order to avoid the risk of progressive disease, the initiation of empirical antituberculous therapy has been suggested for patients with both positive acid-fast bacillus smear microscopy (AFB) and nucleic acid amplification tests (NAATs) pending culture results (25).The diagnostic accuracy of NAATs for AFB-positive samples, however, is still unclear. In a previous meta-analysis of commercially based NAATs, we found that their sensitivities and specificities for AFB-positive samples ranged, among different kits, from 0.96 to 0.98 and from 0.71 to 0.96 and that they were considerably inf...

show abstract

Section: Discussionmentioning

confidence: 99%

Diagnostic Accuracy of In-House PCR for Pulmonary Tuberculosis in Smear-Positive Patients: Meta-Analysis and Metaregression

et al. 2009

View full text Add to dashboard Cite

show abstract

“…Among the approved commercial NAA methods, the amplified M. tuberculosis direct test (MTD test; Gen-Probe) detects M. tuberculosis RNA by using a specific isothermal transcription-mediated amplification method (21). The MTD test has been shown to be a sensitive, specific, and rapid method for use with clinical samples (9,17,18); however, it requires the use of expensive specialized detection equipment, which prevents the assay from being applied widely in clinical laboratories. The aim of this study was to report and evaluate a simultaneous amplification and testing method for detection of the M. tuberculosis complex (SAT-TB assay) for use with clinical sputum specimens, based on real-time fluorescence detection of isothermal RNA amplification using routine real-time PCR equipment.…”

mentioning

confidence: 99%

Novel Real-Time Simultaneous Amplification and Testing Method To Accurately and Rapidly Detect Mycobacterium tuberculosis Complex

Cui

Wang²,

Fang

et al. 2012

J Clin Microbiol

View full text Add to dashboard Cite

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.T he rapid and accurate diagnosis of pulmonary tuberculosis (PTB) plays a critical role in its successful management, as it is essential to treat patients with the appropriate therapy as soon as possible to minimize the risk of transmission. A number of tests based on nucleic acid amplification (NAA) have been developed to identify Mycobacterium tuberculosis in clinical specimens rapidly and directly (8,34,35,44). Among the approved commercial NAA methods, the amplified M. tuberculosis direct test (MTD test; Gen-Probe) detects M. tuberculosis RNA by using a specific isothermal transcription-mediated amplification method (21). The MTD test has been shown to be a sensitive, specific, and rapid method for use with clinical samples (9, 17, 18); however, it requires the use of expensive specialized detection equipment, which prevents the assay from being applied widely in clinical laboratories. The aim of this study was to report and evaluate a simultaneous amplification and testing method for detection of the M. tuberculosis complex (SAT-TB assay) for use with clinical sputum specimens, based on real-time fluorescence dete...

show abstract

“…Two commonly 87,88 Findings on the NAA test often remain positive after cultures become negative during therapy and can remain positive even after completion of therapy 89 ; therefore, it should not be used for assessing infectivity or response to treatment. culTurE Culture remains the criterion standard for laboratory confirmation of TB.…”

Section: Smear Microscopymentioning

confidence: 99%

Current Concepts in the Management of Tuberculosis

Sia

Wieland

2011

Mayo Clinic Proceedings

150

102

View full text Add to dashboard Cite

E ffective medical therapy for tuberculosis (TB) has existed for more than half a century, yet TB remains among the most pressing public health issues of our day. Tuberculosis is, in part, a disease of poverty. 1 The fact that it remains the eighth leading cause of death in the world speaks to the challenges facing practitioners and public health officials as they try to control a disease that is so entwined in the cultural and economic fabric of society. Challenges to effective solutions include lack of access to diagnosis and treatment, the frequent coexistence of epidemics of TB and human immunodeficiency virus (HIV), and the Tuberculosis (TB) poses a serious threat to public health throughout the world but disproportionately afflicts low-income nations. Persons in close contact with a patient with active pulmonary TB and those from endemic regions of the world are at highest risk of primary infection, whereas patients with compromised immune systems are at highest risk of reactivation of latent TB infection (LTBI). Tuberculosis can affect any organ system. Clinical manifestations vary accordingly but often include fever, night sweats, and weight loss. Positive results on either a tuberculin skin test or an interferon-γ release assay in the absence of active TB establish a diagnosis of LTBI. A combination of epidemiological, clinical, radiographic, microbiological, and histopathologic features is used to establish the diagnosis of active TB. Patients with suspected active pulmonary TB should submit 3 sputum specimens for acidfast bacilli smears and culture, with nucleic acid amplification testing performed on at least 1 specimen. For patients with LTBI, treatment with isoniazid for 9 months is preferred. Patients with active TB should be treated with multiple agents to achieve bacterial clearance, to reduce the risk of transmission, and to prevent the emergence of drug resistance. Directly observed therapy is recommended for the treatment of active TB. Health care professionals should collaborate, when possible, with local and state public health departments to care for patients with TB. Patients with drug-resistant TB or coinfection with human immunodeficiency virus should be treated in collaboration with TB specialists. Public health measures to prevent the spread of TB include appropriate respiratory isolation of patients with active pulmonary TB, contact investigation, and reduction of the LTBI burden. Proc. 2011;86(4):348-361 AFB = acid-fast bacilli; BCG = bacille Calmette-Guérin; CFP-10 = culture filtrate protein 10; DOT = directly observed therapy; EMB = ethambutol; ESAT-6 = early-secreted antigenic target 6; HIV = human immuno deficiency virus; IFN-γ = interferon-γ; IGRA = IFN-γ release assay; INH = isoniazid; LTBI = latent TBI; MDR-TB = multidrug-resistant TB; NAA = nucleic acid amplification; PZA = pyrazinamide; RIF = rifampin; TB = tuberculosis; TBI = TB infection; TST = tuberculin skin test; XDR-TB = extensively drug-resistant TB Mayo Clin

show abstract

Use of the Amplified Mycobacterium tuberculosis Direct Test in a Public Health Laboratory

Cited by 50 publications

References 11 publications

Diagnostic Accuracy of In-House PCR for Pulmonary Tuberculosis in Smear-Positive Patients: Meta-Analysis and Metaregression

Diagnostic Accuracy of In-House PCR for Pulmonary Tuberculosis in Smear-Positive Patients: Meta-Analysis and Metaregression

Novel Real-Time Simultaneous Amplification and Testing Method To Accurately and Rapidly Detect Mycobacterium tuberculosis Complex

Current Concepts in the Management of Tuberculosis

Contact Info

Product

Resources

About