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

Authors

  • 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

27-08-2019

Issue

Section

Original Articles

How to Cite

1.
Malik MI, Ejaz T, Ahmed J, Arshad K, Jamal Y, Zohfreen Z. DIAGNOSTIC ACCURACY OF GENEXPERT ASSAY AND COMPARISON WITH SMEAR AFB ON BRONCHIAL WASHINGS IN SPUTUM NEGATIVE SUSPECTED PULMONARY TUBERCULOSIS. Pak Armed Forces Med J [Internet]. 2019 Aug. 27 [cited 2024 Jun. 18];69(4):857-62. Available from: https://pafmj.org/PAFMJ/article/view/3214