Skip to main content
The Egyptian Journal of Bronchology
Download PDF

Valuing the use of GeneXpert test as an unconventional approach to diagnose pulmonary tuberculosis

Egyptian Journal of Bronchology volume 13, pages 403–407 (2019)Cite this article

Abstract

Background

A rapid, highly sensitive, and qualitative diagnostic test will significantly reduce the incidence of tuberculosis (TB). GeneXpert test is the test that is supposed to play this role with those specifications.

Objective

Our goal was to assess the precision of the GeneXpert test in the diagnosis of pulmonary TB.

Patients and methods

This cross-sectional analytic study was carried out at Assiut University Hospital in collaboration with Assiut Chest Hospital, Assiut, Egypt. A total of 67 patients of suspected pulmonary TB were included. For microbiological examination, two sputum samples were obtained from each patient within the same day. One sample was collected at Assiut University Hospital and subjected to smear microscopy by Ziehl—Neelsen staining and culture on Lowenstein—Jensen media. The other sample was taken at Assiut Chest Hospital to be processed for GeneXpert Mycobacterium tuberculosis/rifampicin assay. The culture was applied as a confirmatory test to evaluate the Xpert Mycobacterium tuberculosis/rifampicin assay test.

Results

GeneXpert had 95.9% sensitivity and 94.4% specificity in diagnosing pulmonary TB with the area under the curve of 0.95 and overall diagnostic accuracy of 95.5%. Ziehl—Neelsen examination had 65.3% sensitivity and 100% specificity with the area under the curve of 0.83 and overall diagnostic accuracy of 74.6. For smear-negative, culture-positive cases, GeneXpert showed sensitivity of 94.1%. False-positive GeneXpert for TB was recorded in just one patient.

Conclusion

The GeneXpert test is accurate in diagnosing pulmonary TB and its greatest benefit is clearly demonstrated in smear-negative TB cases. However, the test is not free from some fallacies, even if they are a few, which draws our attention to the importance of the conventional culture for TB and the clinical correlation.

References

  1. Maartens G, Wilkinson RJ. Tuberculosis. Lancet 2007; 370:2030–2043.

    Article  Google Scholar 

  2. Raviglione M, Sulis G. Tuberculosis 2015:burden, challenges and strategy for control and elimination. Infect Dis Rep 2016; 8:33–37.

    Article  Google Scholar 

  3. Alaarag AH, Mohammad OI, Farag NM. Diagnostic utility of serum adenosine deaminase level in the diagnosis of pulmonary tuberculosis. Egypt J Bronchol 2016; 10:133–139.

    Article  Google Scholar 

  4. World Health Organization. Global tuberculosis report. Geneva:WHO; 2016.

    Google Scholar 

  5. Munir MK, Anwar N, Iqbal R, Shabbir I, Nosheen S. Diagnosis of tuberculosis:molecular versus conventional method. Pak J Med Res 2011; 50:50.

    Google Scholar 

  6. Helb D, Jones M, Story E, Boehme C, Wallace E, Ho K, et al. Rapid detection of Mycobacterium tuberculosis and rifampin resistance by use of on-demand, near-patient technology. J Clin Microbiol 2010; 48:229–237.

    Article  CAS  Google Scholar 

  7. International Union against Tuberculosis and Lung Disease. Sputum examination for tuberculosis by direct microscopy in low income countries. Technical GUIDE. 5th ed. Paris, France:IUATLD; 2000.

    Google Scholar 

  8. Chihota VN, Grant AD, Fielding K, Ndibongo B, van Zyl A, Muirhead D, et al. Liquid vs. solid culture for tuberculosis:performance and cost in a resource-constrained setting. Int J Tuberc Lung Dis 2010; 14:1024–1031.

    CAS  PubMed  Google Scholar 

  9. Boehme CC, Nabeta P, Hillemann D, Nicol MP, Shenai S, Krapp F, et al. Rapid molecular detection of tuberculosis and rifampin resistance. N Eng J Med 2010; 363:1005–1015.

    Article  CAS  Google Scholar 

  10. Tuberculosis Division International Union against Tuberculosis and Lung Disease. Tuberculosis bacteriology—priorities and indications in high prevalence countries:position of the technical staff of the Tuberculosis Division of the International Union against Tuberculosis and Lung Disease. Int J Tuberc Lung Dis 2005; 9:355–361.

    Google Scholar 

  11. World Health Organization. WHO laboratory services in tuberculosis control. Part II:microscopy. Geneva:WHO; 1998. 30–32

    Google Scholar 

  12. Bruchfeld J, Aderaye G, Palme IB, Bjorvatn B, Kallenius G, Lindquist L. Sputum concentration improves diagnosis of tuberculosis in a setting with a high prevalence of HIV. Trans R Soc Trop Med Hyg 2000; 94:677–680.

    Article  CAS  Google Scholar 

  13. Murray SJ, Barrett A, Magee JG, Freeman R. Optimization of acid fast smears for the direct detection of mycobacteria in clinical samples. J Clin Pathol 2003; 56:613–615.

    Article  CAS  Google Scholar 

  14. Peterson EM, Nakasone A, Platon-DeLeon JM, Jang Y, de La Maza LM, Desmond E. Comparison of direct and concentrated acid-fast smears to identify specimens culture positive for Mycobacterium spp. J Clin Microbiol 1999; 37:3564–3568.

    Article  CAS  Google Scholar 

  15. Woods GL, Pentony E, Boxley MJ, Gatson AM. Concentration of sputum by cytocentrifugation for preparation of smears for detection of acid-fast bacilli does not increase sensitivity of the fluorochrome stain. J Clin Microbiol 1995; 33:1915–1916.

    Article  CAS  Google Scholar 

  16. Saceanu CA, Pfeiffer NC, McLean T. Evaluation of sputum smears concentrated by cytocentrifugation for detection of acid-fast bacilli. J Clin Microbiol 1993; 31:2371–2374.

    Article  CAS  Google Scholar 

  17. Somoskovi A, Hotaling JE, Fitzgerald M, O’Donnell D, Parsons LM, Salfinger M. Lessons from a proficiency testing event for acid-fast microscopy. Chest 2001; 120:250–257.

  18. Steingart KR, Henry M, Vivienne Ng, Hopewell PC, Ramsay A, Cunningham J, et al. Fluorescence versus conventional sputum smear microscopy for tuberculosis:a systematic review. Lancet Infect Dis 2006; 6:570–581.

    Article  Google Scholar 

  19. Steingart KR, Schiller I, Horne DJ, Pai M, Boehme CC, Dendukuri N. Xpert (R) MTB/RIF assay for pulmonary tuberculosis and rifampicin resistance in adults. Cochrane Database Syst Rev 2014; 1:CD009593.

  20. Zumla A, George A, Sharma V, Herbert RHN, Ilton BM, Oxley A, et al. The WHO 2014 global tuberculosis report—further to go. Lancet Glob Health 2015; 3:e10–e12.

    Article  Google Scholar 

  21. Detjen AK, DiNardo AR, Leyden J, Steingart KR, Menzies D, Schiller I, et al. Xpert MTB/RIF assay for the diagnosis of pulmonary tuberculosis in children:a systematic review and meta-analysis. Lancet Resp Med 2015; 3:451–461.

    Article  Google Scholar 

  22. Darwish M, Magda AEW, Hazem A. Diagnostic assessment of Xpert MTB/RIF in sample of Mycobacterium tuberculosis. Egyptian patients. Afr J Microbiol Res 2013; 7:5107–5113.

    CAS  Google Scholar 

  23. Meawed TE, Shaker A. Assessment of diagnostic accuracy of GeneXpert MTB/RIF in diagnosis of suspected retreatment pulmonary tuberculosis patients. Egypt J Chest Dis Tub 2016; 65:637–641.

    Article  Google Scholar 

  24. Moussa SM, Bayoumi FS, Ali AM. Evaluation of GeneXpert MTB/RIF assay for direct diagnosis of pulmonary tuberculosis. Saudi Med J 2016; 37:1076–1081.

    Article  Google Scholar 

  25. Theron G, Venter R, Calligaro G, Smith L, Limberis J, Meldau R, et al. Xpert MTB/RIF results in patients with previous tuberculosis:can we distinguish true from false positive results? Clin Infect Dis 2016; 62:995–1001.

    Article  CAS  Google Scholar 

  26. Boyles T, Hughes J, Cox V, Burton R, Meintjes G, Mendelson M. False-positive Xpert® MTB/RIF assays in previously treated patients:need for caution in interpreting results. Int J Tuberc Lung Dis 2014; 18:876–878.

    Article  CAS  Google Scholar 

  27. Kelly JD, Grace Lin SY, Barry PM, Keh C, Higashi J, Metcalfe JZ. Xpert MTB/RIF false detection of rifampin-resistant tuberculosis from prior infection. Am J Respir Crit Care Med 2014; 190:1316–1318.

    Article  Google Scholar 

  28. Stevenson DR, Biswas JR, Lievesley A, Quinn G, Buckley J, John L, et al. False-positive Xpert® MTB/RIF more than seven years after cure. Int J Tuberc Lung Dis 2015; 19:1264–1265.

    Article  CAS  Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Department of Chest, Faculty of Medicine, Assiut University, Assiut, Egypt

    Amany Omar, Abd-Elazim Abo Elfadl, Yousef Ahmed & Moustafa Hosny

Authors
  1. Amany Omar
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Abd-Elazim Abo Elfadl
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Yousef Ahmed
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Moustafa Hosny
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Yousef Ahmed.

Additional information

This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms.

Rights and permissions

This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Omar, A., Elfadl, AE.A., Ahmed, Y. et al. Valuing the use of GeneXpert test as an unconventional approach to diagnose pulmonary tuberculosis. Egypt J Bronchol 13, 403–407 (2019). https://doi.org/10.4103/ejb.ejb_88_18

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.4103/ejb.ejb_88_18

Keywords