DIAGNOSTIC ACCURACY OF GENEXPERT ASSAY AND COMPARISON WITH SMEAR AFB ON BRONCHIAL WASHINGS IN SPUTUM NEGATIVE SUSPECTED PULMONARY TUBERCULOSIS

  • Mahmood Iqbal Malik Pak Emirates Military Hospital/National University of Medical Sciences (NUMS) Rawalpindi Pakistan
  • Taymmia Ejaz Pak Emirates Military Hospital/National University of Medical Sciences (NUMS) Rawalpindi Pakistan
  • Jamal Ahmed Pak Emirates Military Hospital/National University of Medical Sciences (NUMS) Rawalpindi Pakistan
  • Komal Arshad Pak Emirates Military Hospital/National University of Medical Sciences (NUMS) Rawalpindi Pakistan
  • Yousaf Jamal Pak Emirates Military Hospital/National University of Medical Sciences (NUMS) Rawalpindi Pakistan
  • Zeenat Zohfreen Pak Emirates Military Hospital/National University of Medical Sciences (NUMS) Rawalpindi Pakistan
Keywords: Bronchoalveolar lavage fluid/microbiology, Bronchoscopy, Tuberculosis

Abstract

Objective: To determine diagnostic accuracy of GeneXpert Assay and compare it with smear microscopy for AFB in terms of sensitivity, specificity on bronchial washings/bronchoalveolar lavage samples in sputum smear negative suspected tuberculosis.

Study Design: A prospective cross sectional analytical study.

Place and Duration of Study: Pulmonology Department, Pak Emirates Military Hospital Rawalpindi, from Jul to Dec 2018.

Materials and Methods: Patients older than 12 years with suspected sputum negative tuberculosis were included in the study. Bronchoscopy findings were noted, bronchoalveolar lavage fluid/bronchial washings were taken. Samples were sent for AFB smear; GeneXpert Assay and Cultures. Data was analyzed in SPSS version 23.

Results: A total of 224 patients were included in the study. 151 (67.4%) were males and 73 (32.6%) females. Mean age was 48.25 ± SD 18.21. Flexible bronchoscopy was diagnostic for tuberculosis in overall 42.4% (95/224) cases. Smear microscopy for AFB was positive in 53 (23.7%) cases, GeneXpert in 82 (36.6%) cases, culture in 66 (29%) cases while 6 cases (2.7%) showed rifampicin resistance on GeneXpert RIF resistance assay. Sensitivity, specificity, PPV and NPV of smear microscopy were 69.6%, 95.5%, 86.7%, 88.3% respectively whereas for GeneXpert they were 86.36%, 84.1%, 69.5%. 93.66% respectively; when compared to culture considered as gold standard. GeneXpert assay activity had statistically significant (p-value<0.01) association with smear and culture positivity.

Conclusion: GeneXpert assay had higher sensitivity than AFB smear microscopy and it is a rapid and effective tool on bronchial washings, reducing the time constraint associated with culture based diagnosis and determining Rifampin Resistance simultaneously.

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Published
2019-08-27
How to Cite
Malik, M., Ejaz, T., Ahmed, J., Arshad, K., Jamal, Y., & Zohfreen, Z. (2019). DIAGNOSTIC ACCURACY OF GENEXPERT ASSAY AND COMPARISON WITH SMEAR AFB ON BRONCHIAL WASHINGS IN SPUTUM NEGATIVE SUSPECTED PULMONARY TUBERCULOSIS. Pakistan Armed Forces Medical Journal, 69(4), 857-62. Retrieved from https://pafmj.org/index.php/PAFMJ/article/view/3214
Section
Original Articles