ABSTRACT
Tuberculosis [TB] is now a major cause of mortality and morbidity in the world. Nowadays, different methods are used to diagnose tuberculosis. Although classical microbiological methods [such as sputum smear] are specific, they have little sensitivity and the culture is also time-consuming. Using Polymerase Chain Reaction [PCR] in blood samples in terms of Mycobacterium tuberculosis DNA, this study examines diagnostic power of this test in the diagnosis of pulmonary tuberculosis compared with other standard methods. In a cross-sectional descriptive-analytic study, blood samples were taken from 40 TB patients and 40 non-TB cases. Following DNA extraction by the commercial kit QIAGEN, the PCR assay was performed using IS6110 primer. In this study, there were 80 people in two groups of TB and non-TB cases. Each group composed of 14 men [35%] and 26 women [65%]. Sensitivity, specificity as well as positive and negative predictive values obtained 37.5, 100, 100 and 61.5%, respectively. Despite high costs of using PCR for TB diagnosis, sensitivity of this method is low due to various factors and cannot replace current standard methods for TB diagnosis such as smear and culture. It can only be used as a complementary method to confirm diagnosis in strongly suspected cases of tuberculosis