PCR as a diagnostic tool for extra-pulmonary tuberculosis

Abstract

Introduction: Extra-Pulmonary Tuberculosis (EPTB) accounts for approximately 40% of the tuberculosis cases. Though it is not communicable, it is a significant cause of morbidity. This study was conducted to know the efficacy of the Polymerase Chain Reaction (PCR) as an additional tool, along with the con- ventional methods, in the diagnosis of EPTB. Materials and Methods: Clinical samples were collected from suspected cases of EPTB. The Ziehl-Neelsen staining (ZNS), culture on the Lowenstein-Jensen medium (LJM) and PCR testing with the use of a commercial kit were performed on the homogenized samples. Results: A total of 182 samples which were received for the molecular diagnosis of EPTB were also tested by ZNS and cul- ture on LJM for the presence of Mycobacterium tuberculosis. Of these, 22 were positive by at least one of the tests which were used. PCR detected the maximum number of cases of EPTB, followed by culture. The results of PCR and the conven- tional tests were analyzed by using McNemar’s test for the cor- related proportions-the exact method of ‘IBM SPSS Statistics 20’. The analysis showed a statistical significance. Conclusions: Whenever they are feasible, using all the avail- able tests in combination increases the laboratory detection rates of M. tuberculosis from clinical samples. PCR must be included in the diagnostic panel of EPTB.