Comparative Sensitivity of Smear Microscopy for AFB Versus Gene Xpert/RIF Assay on Endrobronchial Washings of the Sputum Smear Negative/Sputum Scarce Patients with Suspected Pulmonary Tuberculosis


  • Sohail Khan Raja
  • Raza Ullah
  • Syed Wasib Shah
  • Shumaila Ambreen
  • Haleema Khan
  • Maria Habib


PTB, Gene Xpert, Sputum Microscopy


Background: Pulmonary Tuberculosis (PTB) is a highly prevalent infectious disease. It can be diagnosed with various tests including sputum ZN staining, Gene Xpert and culture.Objective: The objective of this study is to determine the sensitivity of smear microscopy (SM) for AFB and Gene Xpert MTB/RIF assay in diagnosing PTB in sputum negative and sputum scarce patients on endobronchial washings collected by fibreoptic bronchoscope, in comparison to culture for mycobacterium.Mathodology: This Cross Sectional Study was conducted at Pulmonology department, Military Hospital Rawalpindi (MH-Rawalpindi). Patients of both gender, aged 18-70 years and sputum smear negative PTB suspects were included in the study.  Diagnosed or already on antituberculous treatment patients and Imunocompromised patients (HIV) were excluded.Endobronchial washings were collected from affected segment from all patients using fiber-optic bronchoscopy. Specimen was divided into 3 parts. Each was sent for ZN-microscopy for AFB, MTB gene Xpert and culture.Data was analyzed in SPSS version-20. Frequency and percentages were calculated for qualitative variables like gender, sensitivity of SM for AFB/Gene Xpert. Mean ± standard deviation was calculated for quantitative variables like age, duration of illness. . Post stratification Chi-square test was applied.Results: Mean age was 45.75±17.73 years. 248(74.5%) were male and 85(25.5%) female. Sensitivity and Specificity of BAL smear microscopy was 75.44% and 86.59% while that of Gene XPERT was 94.74% and 80.43% respectively.Conclusion: Results of this study showed that Gene Xpert is more accurate than BAL smear microscopy in predicting PTB.

Author Biography

Sohail Khan Raja

principal author






Original Article