PCR and Elisa methods (IgG and IgM): their comparison with conventional techniques for diagnosis of Mycobacterium tuberculosis.

In order to establish a rapid and stable method for diagnosis of Mycobacterium tuberculosis infection and minimize the side effects of delayed diagnosis on patients and health system, a cross sectional study was carried out. Since, the infection rate with this bacteria increasing and one of the reasons for this increase is long process of laboratory identification, therefore establishing new diagnosis methods could decrease disease rate. To achieve this aim, collected sputum and blood specimens from 50 patients with clinical suspicion of pulmonary tuberculosis were studied with both traditional, acid-fast stain (AFB) and culture method compare to Enzyme-linked immunosorbent assay (Elisa) (IgG and IgM) and Polymerase Chain Reaction (PCR) methods. The sensitivity and specificity of all methods were determined by using the PCR results as the gold standard. The overall sensitivity, specificity, positive predictive value and negative predictive value of AFB were 17.64, 100, 100 and 70.12%. These values for culture method was 29.41, 100, 100 and 73.33% and for IgG antibody were 66.7, 81.81, 64.7 and 81.81% and IgM antibody were 70.58, 90.9, 80 and 85.71%, respectively. It was concluded that maximum sensitivity and specificity can be achieved by PCR method.