Diagnostic Performance of Polymerase Chain Reaction Targeting Insertion Sequence (IS6110) for the Detection of Extra Pulmonary Tuberculosis

Abstract

The diagnostic challenges in extra-pulmonary tuberculosis remain to be addressed even though remarkable progress has been made in the diagnostics of pulmonary tuberculosis during the last decade. Methods: This study was conducted to evaluate the use of polymerase chain reaction (PCR) in diagnosis of definitive extra pulmonary tuberculosis patients, and to assess the performance of insertion sequence (IS)6110 based PCR assay as compared to conventional liquid culture by Microbial growth Indicator Tube (MGIT) 960 system. Results: A total of 792 clinical specimens were collected from clinically suspected extra pulmonary tuberculosis patients. The specimens included 22 ascitic fluids, 69 pleural fluids, 240 Cerebrospinal fluids (CSF), 386 endometrial tissues, 47 lymph nodes, 22 pus, one synovial fluid, one fallopian tube, two brain abscess and two ovarian cyst samples. All these clinical samples were subjected to Auromine O staining (FM) for acid fast bacilli (AFB) and culture on MGIT 960 tubes containing Modified Middlebrooks 7H9 broth medium. PCR was performed by targeting 123bp fragment of insertion sequence IS6110 of Mycobacterium tuberculosis. Our study of 792 specimens, revealed their 87.5% sensitivity to endometrial samples, 92.31% sensitivity for cerebrospinal fluid, and 66.66% sensitivity in Pleural fluid and 60% sensitivity in Lymph node samples. The combined sensitivity and specificity of the PCR IS6110 was calculated to be 85.71% and 82.91%, respectively. Conclusion: PCR using IS6110 primer was able to pick up more positivity in extra pulmonary samples as compared to conventional culture method for the detection of M. tuberculosis.

Effectiveness of Polymerase chain reaction in Ziehl-Neelsen stain negative body fluids samples in suspected cases of Extra Pulmonary Tuberculosis

“…Many reports have demonstrated the value of PCR in the diagnosis of extrapulmonary tuberculosis, including pleural effusion and lymphadenitis. (7,11,12) However, the presence of PCR inhibitors in clinical samples hampers the use of amplification techniques with full confidence and ease (7,13), and there is a pressing need for a robust, reproducible, and uniform method of inhibitor removal from clinical specimens (sputum, fluids, and tissues). The present study was undertaken to find the effectiveness of Polymerase Chain Reaction and culture on Ziehl-Neelsen stain negative samples of body fluids for rapid diagnosis of suspected cases of Extrapulmonary Tuberculosis.…”