Comparison of Two Molecular Methods for Rapid Diagnosis of Extrapulmonary Tuberculosis

Causse, Manuel; Ruiz, Pilar; Gutiérrez-Aroca, Juan; Casal, Manuel

doi:10.1128/jcm.00491-11

Cited by 122 publications

(122 citation statements)

References 14 publications

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“…Culture, however, is limited in its ability to detect EPTB and the comparison to only cultureconfirmed cases is likely to overestimate the sensitivity of Xpert. Nonetheless, in our study Xpert missed all cases with positive cultures on tissue.The low sensitivity in pleural fluid observed in this study has been described in previous studies [5][6][7]10]. Explanations for the limited sensitivity of Xpert in pleural fluid and tissue samples could relate to PCR inhibitors or insufficient sample volume in this paucibacillary disease.…”

supporting

confidence: 69%

“…The low sensitivity in pleural fluid observed in this study has been described in previous studies [5][6][7]10]. Explanations for the limited sensitivity of Xpert in pleural fluid and tissue samples could relate to PCR inhibitors or insufficient sample volume in this paucibacillary disease.…”

supporting

confidence: 69%

“…lymph node), suggesting that it could be an alternative to culture in tissue specimens [7]. Most of these studies have used only a culture reference standard [10]. Culture, however, is limited in its ability to detect EPTB and the comparison to only cultureconfirmed cases is likely to overestimate the sensitivity of Xpert.…”

mentioning

confidence: 99%

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Performance of Xpert MTB/RIF on pleural tissue for the diagnosis of pleural tuberculosis

et al. 2013

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Tuberculosis (TB) remains the second leading cause of death from an infectious disease in adults. Extrapulmonary TB (EPTB) accounts for about 25% of all cases of active TB. Pleural TB is the second most common manifestation of EPTB.Existing tests for the diagnosis of pleural TB have major limitations in terms of accuracy, time to diagnosis and drug resistance testing, and require special expertise for sample acquisition and interpretation of the results. Biopsy of the pleural tissue for combined histological examination and culture is considered the diagnostic gold standard, albeit imperfect [1,2].The Xpert MTB/RIF assay (Xpert; Cepheid, Sunnyvale, CA, USA) is a rapid, World Health Organization (WHO) endorsed, automated PCR test optimised for respiratory specimens that can detect both Mycobacterium tuberculosis (MTB) and rifampicin resistance [3,4]. Given the limitations of available tests for the diagnosis of pleural TB, several studies have evaluated the performance of Xpert using pleural fluid as a sample type. Overall, these studies show limited accuracy with sensitivity averaging around 44% [5][6][7]. However, the preferred specimen for the diagnosis of pleural TB is pleural tissue. To date, the evaluation of Xpert performed on pleural tissue has been limited to isolated samples within larger studies [4,6,7].We enrolled consecutive adult patients that were evaluated for pleural TB in the pulmonary clinic and inpatient ward at the Christian Medical College, Vellore, India. Pleural TB was suspected based on clinical symptoms and radiographic evidence of a pleural effusion. Information on demographics, comorbidities, presenting symptoms and results of diagnostic evaluation were collected prospectively. The institutional review boards of the Christian Medical College and McGill University, Montreal, Canada, approved the study.All recruited patients underwent thoracentesis for evaluation of pleural fluid. One specimen was processed with routine diagnostics including fluorescence smear microscopy, adenosine deaminase (ADA; Diazyme Laboratories, San Diego, CA, USA), liquid cultures (Mycobacterium Growth Indicator Tube; Becton Dickinson, Sparks, MD, USA) and solid cultures (Löwenstein-Jensen medium). The second sample was used for Xpert testing. A pleural biopsy was performed, when clinically indicated and safely feasible. Pleural tissue was evaluated with histopathology, smear microscopy and culture. : sensitivity 0% (none out of 17; 95% CI 0-20%) and specificity 97.4% (37 out of 38; 95% CI 86-100%). 1427Pleural fluid was centrifuged (1370 6g for 15 min) and the concentrated sediment, resuspended in 1 mL of the original supernatant, was used for Xpert [5]. Pleural tissue was finely ground and re-suspended in 1 mL of sterile saline [8]. The Xpert ''sample reagent'' was added (2:1 ratio for both pleural fluid and pleural tissue samples) and, after incubation, 2 mL were transferred into a G4 cartridge.We defined two composite reference standards (CRS) for the diagnosis of TB. The first CRS (CRS-1) identified confirme...

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Performance of Xpert MTB/RIF on pleural tissue for the diagnosis of pleural tuberculosis

et al. 2013

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“…In a third paper, excellent Xpert results (95% sensitivity and 100% specificity) have been reported for 340 extrapulmonary specimens; however, separate analysis for different specimen types was not provided [13].…”

Section: Discussionmentioning

confidence: 99%

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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“…We selected 15 studies for inclusion (figure 1). [12][13][14][15][16][17][18][19][20][21][22][23][24][25] Five studies were done in low-income countries, two in lower middle-income, six in upper middle-income, and two in high-income countries (table 1). 26 12 studies were done at tertiary, university, or research facilities.…”

Section: Resultsmentioning

confidence: 99%

Xpert MTB/RIF assay for the diagnosis of pulmonary tuberculosis in children: A systematic review and meta-analysis

2015

Indian Journal of Tuberculosis

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Comparison of Two Molecular Methods for Rapid Diagnosis of Extrapulmonary Tuberculosis

Cited by 122 publications

References 14 publications

Performance of Xpert MTB/RIF on pleural tissue for the diagnosis of pleural tuberculosis

Performance of Xpert MTB/RIF on pleural tissue for the diagnosis of pleural tuberculosis

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

Xpert MTB/RIF assay for the diagnosis of pulmonary tuberculosis in children: A systematic review and meta-analysis

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