Comparison of the Diagnostic Accuracy of the Xpert MTB/RIF Assay with Acid-Fast Staining and Culture Methods for Prompt Detection of Mycobacterium tuberculosis Isolates

Nastaran  Momeni; Lida  Mahfoozi; Saman  Maroufizadeh; Paridokht  Karimian; Ezat  Hesni

doi:10.18502/jmb.v13i2.18658

Nastaran Momeni School of Medicine, Guilan University of Medical Sciences, Rasht, Iran
Lida Mahfoozi Infectious Disease Department, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran.
Saman Maroufizadeh Department of Biostatistics, School of Health, Guilan University of Medical Sciences, Rasht, Iran
Paridokht Karimian Pathology Department, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran.
Ezat Hesni Infectious Disease Department, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran.

DOI: https://doi.org/10.18502/jmb.v13i2.18658

Keywords: Acid-fast staining, Culture, Mycobacterium tuberculosis, Xpert MTB/RIF test

Abstract

Background: The aim of this study was to compare the diagnostic accuracy of the GeneXpert with acid-fast stain (AFB) and culture methods in patients with suspected pulmonary tuberculosis (SPT).

Methods: A total of 484 sputum and BALF (bronchoalveolar lavage fluid). Samples were analyzed from 428 individuals, of which 78.3% were men and the average age was 49.9 years.

Results: The GeneXpert test had a sensitivity of 95.7% and a specificity of 43.9% for MTB culture, and a sensitivity of 91.9% and a specificity of 52.8% for a definitive diagnosis. The sample had a sensitivity of 93.7%, specificity of 69.6%, and accuracy of 82.2% for MTB culture, and sensitivity of 86.9%, specificity of 82.2%, and accuracy of 85.3% for the final diagnosis. Overall, the AFB exam had the highest diagnostic accuracy of the three tests at 85.3%.

Conclusion: The study indicates that while the study's AFB test is usually used as the first diagnostic test for pulmonary TB due to its high accuracy, the GeneXpert test can be used in samples that are AFB negative, but strongly suspected for TB, because it has a higher sensitivity. Choosing the appropriate test based on the clinical context is critical for accurate diagnosis and treatment of TB.