Conventional versus molecular methods for diagnosis of tuberculosis in a tertiary care center: A study from Punjab

Abstract

Background: A fast and accurate diagnosis is necessary to control and eliminate tuberculosis (TB). There have been various studies evaluating the efficacy of polymerase chain reaction (PCR) testing in clinical practice. Most of these studies have found PCR as a useful tool to diagnose TB and more so for the extra-pulmonary cases. Aims and Objectives: The aim of the study was to evaluate the results of TB by real-time PCR versus the conventional methods of diagnosis in a tertiary care center in Punjab. Materials and Methods: This study was done in a tertiary care center of Punjab to look for the results of clinical samples tested for TB using PCR, Ziehl–Neelsen staining and culture on Lowenstein–Jensen medium. 16S rRNA gene was used for Mycobacterium tuberculosis detection in PCR. This study included all samples tested for TB from July 2015 to October 2015. Results: A total of 214 samples were tested for TB using smear microscopy, culture and PCR (including 194 [90.6%] extra-pulmonary and 20 [9.3%] pulmonary samples). These included 76 cerebrospinal fluid, 30 pleural fluid, 42 tissues, 17 ascitic fluid, 13 urine, 15 bronchoalveolar lavage (BAL), 16 pus, and 5 sputum samples. Smear microscopy was positive in a total of 4 samples out of 214 (1.8%), which included 2 sputum, 1 tissue, and 1 ascitic fluid samples, while culture was positive for 6 samples (2.8%) which included 2 sputum, 1 pus, 1 BAL, 1 tissue, and 1 ascitic fluid sample. The TB PCR results were positive in a total of 71 (33.1%) samples out of 214. In addition, three samples also tested positive for Mycobacteria other than TB. Conclusion: PCR is a very rapid and accurate diagnostic tool for early detection of TB in particularly for extrapulmonary TB.

Keywords

• Lowenstein–Jensen medium
• real-time polymerase chain reaction
• tuberculosis
• Ziehl–Neelsen staining