Comparison of conventional and molecular methods for diagnosing Tuberculosis in pulmonary non-sputum samples

Abstract

Introduction: One person dies of Tuberculosis every two minutes in India according to WHO report in 2014. Tuberculosis is a horrible scourge of mankind, especially so in case of developing countries like India with poor sanitation conditions. Tuberculosis can affect many other parts of the body apart from lungs. Many newer diagnostic modalities have become available for diagnosing tuberculosis. Objectives: This study was taken up in order to compare conventional and one of the newer techniques, PCR for diagnosing Tuberculosis in non-sputum samples. Material & methods: Non-sputum samples received during the period 1 July 2015 to 31 June 2016 for detection of Mycobacterium tuberculosis were included. Samples comprised of Bronchial wash, Pus, Pleural fluid, Bronchoalveolar lavage fluid, Ultra sound or CT guided fluid and Tissue of suspected Tuberculosis patients. Efficiency of smear microscopy and PCR were compared with the Gold standard culture. Results & Discussion: Though the specificity and negative predictive value of PCR are good, the sensitivity and positive predictive value are greatly different from conventional culture. Conclusion: Inspite of its high sensitivity and specificity, cost is a constraint with PCR. In resourceful settings, PCR and culture used together would fetch faster and reliable results than any diagnostic test used alone.

Keywords

• non-sputum samples
• Ziehl-Neelsen (ZN) technique
• PCR
• gold standard