Performance of Nucleic Acid Amplification Tests for Diagnosis of Tuberculosis in a Large Urban Setting

Laraque, Fabienne; Griggs, Anne; Slopen, Meredith; Munsiff, Sonal S.

doi:10.1086/599037

Cited by 66 publications

(57 citation statements)

References 17 publications

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“…Both reported very good results with important categories of specimens such as CSFs, gastric aspirates and tissue samples and for both the overall sensitivity was high (89.3% and 82.7%, respectively). In the paper by LARAQUE et al [15], however, the high sensitivity was counterbalanced by very poor specificity (74.5%).…”

Section: Discussionmentioning

confidence: 89%

“…For what concerns data obtained with extrapulmonary specimens using commercial NATs other than Xpert, only two studies investigated large numbers of samples [15,16]; similar to the present study, in both studies molecular results were compared to a gold standard combining both culture results and clinical diagnosis. The first evaluated the AMTD (GenProbe, San Diego, CA, USA) on 682 specimens [15], while in the second 918 samples were assayed by the ProbeTec ET (Becton Dickinson) [16].…”

Section: Discussionmentioning

confidence: 92%

“…The first evaluated the AMTD (GenProbe, San Diego, CA, USA) on 682 specimens [15], while in the second 918 samples were assayed by the ProbeTec ET (Becton Dickinson) [16]. Both reported very good results with important categories of specimens such as CSFs, gastric aspirates and tissue samples and for both the overall sensitivity was high (89.3% and 82.7%, respectively).…”

Section: Discussionmentioning

confidence: 99%

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Clinical validation of Xpert MTB/RIF for the diagnosis of extrapulmonary tuberculosis

Tortoli¹,

et al. 2012

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Extrapulmonary tuberculosis (EPTB) accounts for more than 20% of tuberculosis (TB) cases. Xpert MTB/RIF (Xpert) (Cepheid, Sunnyvale, CA, USA) is a fully automated amplification system, for which excellent results in the diagnosis of pulmonary TB in highly endemic countries have been recently reported. We aimed to assess the performance of the Xpert system in diagnosing EPTB in a low incidence setting.We investigated with Xpert a large number of consecutive extrapulmonary clinical specimens (1,476, corresponding to 1,068 patients) including both paediatric (494) and adult samples.We found, in comparison with a reference standard consisting of combination of culture and clinical diagnosis of TB, an overall sensitivity and specificity of 81.3% and 99.8% for Xpert, while the sensitivity of microscopy was 48%. For biopsies, urines, pus and cerebrospinal fluids the sensitivity exceeded 85%, while it was slightly under 80% for gastric aspirates. It was, in contrast, lower than 50% for cavitary fluids. High sensitivity and specificity (86.9% and 99.7%, respectively) were also obtained for paediatric specimens.Although the role of culture remains central in the microbiological diagnosis of EPTB, the sensitivity of Xpert in rapidly diagnosing the disease makes it a much better choice compared to smear microscopy. The ability to rule out the disease still remains suboptimal.

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Section: Discussionmentioning

confidence: 89%

Section: Discussionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 99%

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Clinical validation of Xpert MTB/RIF for the diagnosis of extrapulmonary tuberculosis

Tortoli¹,

et al. 2012

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“…The direct detection of M. tuberculosis complex DNA by PCR-based assays has become an important part of the rapid diagnosis of tuberculosis (4). Numerous molecular assays for the rapid detection of M. tuberculosis complex DNA have been developed.…”

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confidence: 99%

Evaluation of the Cobas TaqMan MTB Test for the Detection of Mycobacterium tuberculosis Complex According to Acid-Fast-Bacillus Smear Grades in Respiratory Specimens

et al. 2015

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We evaluated the performance of the Cobas TaqMan MTB test (Roche Diagnostics, Basel, Switzerland), stratified by acid-fast bacilli (AFB) smear grades. The sensitivity of this test in smear-positive specimens was >95% in all grades, while that in trace and negative specimens was 85.3% and 34.4%, respectively. T he rapid detection of Mycobacterium tuberculosis complex DNA from respiratory specimens and the ability to differentiate M. tuberculosis complex from nontuberculous mycobacteria (NTM) are important for the early diagnosis of pulmonary tuberculosis and the prompt use of adequate antibiotics (1-3). The direct detection of M. tuberculosis complex DNA by PCR-based assays has become an important part of the rapid diagnosis of tuberculosis (4). Numerous molecular assays for the rapid detection of M. tuberculosis complex DNA have been developed. The Cobas TaqMan MTB test (Cobas MTB test) (Roche Diagnostics, Basel, Switzerland) is one of the most widely used realtime PCR assays. It uses TaqMan hydrolysis probes and primers that bind to a highly conserved and specific region of the 16S rRNA sequence.Recently, various rates of detection by different PCR methods, based by smear grade, were noted (5-7). The aim of this study was to investigate whether this observation extends to the Cobas MTB test and to investigate its diagnostic accuracy when stratified by acid-fast bacilli (AFB) smear grades.This study was conducted at a tertiary care hospital in Seoul, South Korea, and was approved by the institutional review board of that hospital. A total of 6,852 Cobas MTB test results for respiratory specimens from April 2013 to June 2014 were retrospectively reviewed. Microbiological tests, including AFB smear and mycobacterial culture, were simultaneously performed for all specimens.The respiratory specimens were processed with 2% N-acetyl-Lcysteine-sodium hydroxide (NALC-NaOH), followed by centrifugation at 3,000 ϫ g for 20 min. The AFB smears were performed with an auramine-rhodamine fluorescent stain and subsequently confirmed by Ziehl-Neelsen staining. The staining results were graded according to the American Thoracic Society/Centers for Disease Control and Prevention (ATS/CDC) guidelines, as follows (8): no AFB seen, no bacilli in 300 fields; trace, 1 to 2 bacilli in 300 fields; 1ϩ, 1 to 9 bacilli in 100 fields; 2ϩ, 1 to 9 bacilli in 10 fields; 3ϩ, 1 to 9 bacilli in 1 field; and 4ϩ, Ͼ9 bacilli in 1 field. The specimens with the no AFB seen and trace grades were defined as smear negative, and those graded 1ϩ to 4ϩ were defined as smear positive. All patient specimens were cultured on both solid and liquid medium for 6 weeks. The positive cultures were confirmed by both the presence of cord formation and by MPT64 antigen testing (SD Bioline TB Ag MPT64 rapid assay; Standard Diagnostics, Inc., Yongin, South Korea). If any of these tests yielded a negative result, an rpoB-specific PCR test using the MTB-ID V3 kit (YD Diagnostics, Yongin, South Korea) was performed to differentiate between M. tuberculosis and NTM. The Cobas...

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“…Here, we report the first comparison of the sensitivity of this novel commercial NAAA with that of an in-house IS6110 real-time PCR using TaqMan probes (IS6110-TaqMan assay) routinely used in our laboratory since 2004 (13). The sensitivities of both assays were mainly determined with paucibacillary specimens (smear negative) culture positive for MTBC because it is well documented that in-house or commercial NAAAs exhibit excellent specificity and high sensitivity with smear-positive specimens but reduced sensitivity with smear-negative specimens, especially nonrespiratory specimens (5,8,12,17,18,19,21). Because CHU Lille, is located in a low-prevalence area for MDR-TB, the accuracy of the Xpert MTB/RIF test was mainly evaluated for the detection of MTBC in specimens that had a rifampinsusceptible isolate.…”

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confidence: 99%

Comparison of the Xpert MTB/RIF Test with an IS 6110 -TaqMan Real-Time PCR Assay for Direct Detection of Mycobacterium tuberculosis in Respiratory and Nonrespiratory Specimens

et al. 2011

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The sensitivities of the Xpert MTB/RIF test and an in-house IS6110-based real-time PCR using TaqMan probes (IS6110-TaqMan assay) for the detection of Mycobacterium tuberculosis complex (MTBC) DNA were compared by use of 117 clinical specimens (97 culture positive and 20 culture negative for MTBC) that were frozen in sediment. The 97 clinical specimens included 60 respiratory and 37 nonrespiratory specimens distributed into 36 smear-positive and 61 smear-negative specimens. Among the 97 culture-positive specimens, 4 had rifampin-resistant isolates. Both methods were highly specific and exhibited excellent sensitivity (100%) with smear-positive specimens. The sensitivity of the Xpert MTB/RIF test with the whole smear-negative specimens was more reduced than that of the IS6110-TaqMan assay (48 versus 69%, P ‫؍‬ 0.005). Both methods exhibited similar sensitivities with smear-negative respiratory specimens, but the Xpert MTB/RIF test had lower sensitivity with smear-negative nonrespiratory specimens than the IS6110-TaqMan assay (37 versus 71%, P ‫؍‬ 0.013). Finally, the sensitivities of the Xpert MTB/RIF test and the IS6110-TaqMan assay were 79% and 84%, respectively, with respiratory specimens and 53% and 78%, respectively (P ‫؍‬ 0.013), with nonrespiratory specimens. The Xpert MTB/RIF test correctly detected the rifampin resistance in smear-positive specimens but not in the one smear-negative specimen. The Xpert MTB/RIF test is a simple rapid method well adapted to a routine laboratory that appeared to be as sensitive as the IS6110-TaqMan assay with respiratory specimens but less sensitive with paucibacillary specimens, such as smear-negative nonrespiratory specimens.Nucleic acid amplification assays (NAAAs) are commonly used in routine laboratories from industrialized countries for quick and specific detection of Mycobacterium tuberculosis complex (MTBC) in clinical specimens. Over the years, a significant improvement of PCR technologies has been achieved with the development of real-time PCR testing platforms. The main advantages of real-time PCR are a shortened turnaround time; automation of the procedure, which reduces hands-on time; and a decrease in the risk of cross-contamination (6). Recently, the GeneXpert system (Cepheid, Sunnyvale, CA), a real-time PCR that simultaneously detects both MTBC and rifampin resistance, was developed (1, 3, 9). In contrast to some real-time PCR instruments, the Xpert MTB/RIF is an on-demand assay described as a simple method that can be performed by personnel with minimal training and can provide results within 2 h (1, 3, 9). Recent studies (3, 9, 15, 16) reported a high sensitivity and specificity of the Xpert MTB/RIF test with respiratory specimens collected from patients living in countries with a high and a low prevalence of tuberculosis (TB). The detection of rifampin resistance, as a surrogate for multidrug-resistant TB (MDR-TB), directly from smear-positive respiratory specimens from patients having a high risk of MDR-TB has recently been recommended by the World Health...

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Performance of Nucleic Acid Amplification Tests for Diagnosis of Tuberculosis in a Large Urban Setting

Abstract: NAA testing was helpful for determining whether patients whose specimens tested positive for AFB on smear had TB or not. This conclusion supports the use of this test for early diagnosis of pulmonary and extrapulmonary TB.

Cited by 66 publications

References 17 publications

Clinical validation of Xpert MTB/RIF for the diagnosis of extrapulmonary tuberculosis

Clinical validation of Xpert MTB/RIF for the diagnosis of extrapulmonary tuberculosis

Evaluation of the Cobas TaqMan MTB Test for the Detection of Mycobacterium tuberculosis Complex According to Acid-Fast-Bacillus Smear Grades in Respiratory Specimens

Comparison of the Xpert MTB/RIF Test with an IS 6110 -TaqMan Real-Time PCR Assay for Direct Detection of Mycobacterium tuberculosis in Respiratory and Nonrespiratory Specimens

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