Real-time PCR assay for the diagnosis of pleural tuberculosis

Our plain-English summary of Real-time PCR assay for the diagnosis of pleural tuberculosis, by M.A. Casallas-Rivera, A.M. Cárdenas Bernal, L.F. Giraldo-Cadavid, et al (Colombia Médica, 2017).

The study

• Authors: M.A. Casallas-Rivera, A.M. Cárdenas Bernal, L.F. Giraldo-Cadavid, E. Prieto Diago, S.P. Santander
• Journal: Colombia Médica
• Published: 2017;48(2):47-52
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Free full text

Abstract

Introduction: The diagnosis of pleural tuberculosis requires an invasive and time-consuming reference method. Polymerase chain reaction (PCR) is rapid, but validation in pleural tuberculosis is still weak.

Objective: To establish the operating characteristics of real-time polymerase chain reaction (RT-PCR) hybridization probes for the diagnosis of pleural tuberculosis.

Methods: The validity of the RT-PCR hybridization probes was evaluated compared to a composite reference method by a cross-sectional study at the Hospital Universitario de la Samaritana. 40 adults with lymphocytic pleural effusion were included. Pleural tuberculosis was confirmed (in 9 patients) if the patient had at least one of three tests using the positive reference method: Ziehl-Neelsen or Mycobacterium tuberculosis culture in fluid or pleural tissue, or pleural biopsy with granulomas. Pleural tuberculosis was ruled out (in 31 patients) if all three tests were negative. The operating characteristics of the RT-PCR, using the Mid-P Exact Test, were determined using the OpenEpi 2.3 Software (2009).

Results: The RT-PCR hybridization probes showed a sensitivity of 66.7% (95% CI: 33.2%-90.7%) and a specificity of 93.5% (95% CI: 80.3%-98.9%). The PPV was 75.0% (95% CI: 38.8%-95.6%) and a NPV of 90.6% (95% CI: 76.6%-97.6%). Two false positives were found for the test, one with pleural mesothelioma and the other with chronic pleuritis with mesothelial hyperplasia.

Conclusions: The RT-PCR hybridization probes had good specificity and acceptable sensitivity, but a negative value cannot rule out pleural tuberculosis.

In plain English

This was a cross-sectional study of a diagnostic test for tuberculosis, not a study of asbestos exposure. At the Hospital Universitario de la Samaritana in Bogotá, Colombia, the authors studied 40 adults hospitalized between September 2009 and September 2012 with a lymphocytic exudate pleural effusion (fluid around the lung). They measured how well a commercial real-time PCR test (M. tuberculosis Real-TM), run on pleural fluid or tissue, identified pleural tuberculosis. They compared it with a combined reference method: culture, Ziehl-Neelsen staining and pleural tissue histology. Nine patients had confirmed pleural tuberculosis. Six of them tested positive by PCR and three tested negative. The test's sensitivity was 66.7% (95% CI 33.2% to 90.7%) and its specificity was 93.5% (95% CI 80.3% to 98.9%). Two of the 31 patients without tuberculosis had false-positive results. One had pleural mesothelioma and the other had chronic pleuritis with mesothelial hyperplasia. The authors concluded that the test had good specificity but should not be used for a definitive diagnosis. They noted that the small sample size widened the confidence intervals.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Cross-sectional diagnostic test accuracy study
• Who was studied: Adults (over 18) hospitalized in the internal medicine service of the Hospital Universitario de la Samaritana, Bogotá, Colombia, with lymphocytic exudate pleural effusion, September 1, 2009 to September 30, 2012. Of 60 patients with pleural effusion, 40 met the inclusion criteria. Nine had confirmed pleural tuberculosis and 31 had tuberculosis ruled out.
• Exposure: No asbestos or fiber exposure was studied. The study evaluated a commercial real-time PCR test with hybridization probes (M. tuberculosis Real-TM) for detecting M. tuberculosis complex DNA in pleural fluid or tissue.
• Main results:
  • Of the 9 patients with confirmed pleural tuberculosis, 6 tested positive and 3 tested negative by RT-PCR.
  • RT-PCR sensitivity was 66.7% (95% CI: 33.2%-90.7%) and specificity was 93.5% (95% CI: 80.3%-98.9%).
  • RT-PCR positive predictive value was 75% (95% CI: 38.8%-95.6%) and negative predictive value was 90.6% (95% CI: 76.6%-97.6%).
  • There were two false-positive RT-PCR results: one in a patient with pleural mesothelioma and one in a patient with chronic pleuritis with mesothelial hyperplasia.
  • In pleural fluid, culture for M. tuberculosis had a sensitivity of 55.6% and Ziehl-Neelsen staining a sensitivity of 22.2%. Both had a specificity of 100%.
  • Among the 31 patients without tuberculosis, 29.0% had effusions associated with neoplasia on pleural biopsy, including three cases of mesothelioma.
• The authors' conclusion: The authors concluded that RT-PCR for M. tuberculosis in pleural fluid has good specificity for diagnosing pleural tuberculosis. Because its predictive values are not high enough, they concluded it should not be used for definitive diagnosis.
• Limitations the authors state:
  • The sample size was small, which widened the confidence intervals and reduced precision.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Pleural plaques and thickening.

Medical terms in this study, explained in our Lexicon: Pleural Effusion, Pleural Biopsy, Granuloma, Pleural Mesothelioma, Reactive Mesothelial Hyperplasia.

Related studies

• Tissue Xpert™ MTB/Rif assay is of limited use in diagnosing peritoneal tuberculosis in patients with exudative ascites — C. Bera, J.S. Michael, et al. (2015)
• Diagnostic value of biochemical ratios in the differential diagnosis of tuberculous and malignant pleural effusions — U. İlhan, Z. Güney, et al. (2026)
• Expression Profiles of Cytokine mRNAs in the Pleural Fluid Reveal Differences Among Tuberculosis, Malignancies, and Pneumonia-Exudative Pleural Effusions — D.L. Espósito, V.R. Bollela, et al. (2015)
• Evaluation of ALS assay of TB-SA for diagnosis of pulmonary tuberculosis — J. Jiao, M.S. Wang, et al. (2015)
• Semi-Rigid Thoracoscopic Punch Biopsy Using a Hybrid Knife with a High-Pressure Water Jet for the Diagnosis of Pleural Effusions — Y. Yin, R. Eberhardt, et al. (2016)
• Prospective Study of the Utility of Computed Tomography Triage of Pleural Biopsy Strategies in Patients With Pleural Diseases — M. Metintas, G. Ak, et al. (2019)

Browse return to medical research.