Role of Real Time Polymerase Chain Reaction Targeting mpb64 Gene in the Diagnosis of Genitourinary Tuberculosis: A Cross-sectional Study

Abstract

Introduction: Genitourinary Tuberculosis (GUTB) remains an important cause of infertility in India. The clinical manifestations of GUTB are non specific, resulting in delayed diagnosis and initiation of Anti Tubercular Treatment (ATT). This delay can lead to various complications such as kidney dysfunction, ureteral strictures, and a shrunken bladder. Aim: To evaluate the diagnostic importance of Real Time Polymerase Chain Reaction (RT-PCR) targeting the mpb64 gene for the rapid and accurate diagnosis of GUTB. Materials and Methods: A cross-sectional hospital-based observational study was conducted in the Department of Microbiology at Subharti Medical College and associated Chhatrapati Shivaji Subharti Hospital in Meerut, Western Uttar Pradesh, India. The study was conducted over a three-year period, from January 2019 to December 2021. A total of 200 genitourinary samples were collected from female patients with clinical suspicion of Tuberculosis (TB) and subjected to direct microscopy, mycobacterial culture by BacT/Alert 3D (Biomerieux, France), and RT-PCR targeting the mpb64 gene (Qiagen). Demographic details were recorded in a predesigned proforma. Statistical analysis was performed using the Statistical Package for Social Sciences (SPSS) software version 26.0 (IBM Corp., Armonk, NY, USA). The p-value was calculated using the Chi-square test. Results: RT-PCR showed a higher positivity rate of 56 (28.9%) compared to 47 (24.2%) by culture. Acid Fast Bacilli (AFB) microscopy was the least sensitive, detecting only 7 (3.6%) cases. When comparing the results of RT-PCR with conventional methods, RT-PCR had a sensitivity, specificity, Positive Predictive Value (PPV), and Negative Predictive Value (NPV) of 91.9%, 99.4%, 85.1%, and 93.8%, respectively. Conclusion: RT-PCR targeting the mpb64 gene is a specific and effective additional test that aids in the early and accurate diagnosis of Extrapulmonary Tuberculosis (EPTB), including GUTB, compared to conventional methods. Early diagnosis facilitates timely initiation of ATT, leading to better clinical outcomes.

Keywords

• extrapulmonary tuberculosis
• molecular diagnosis of tuberculosis
• mycobacterium tuberculosis