Detection of Antibodies Against 6, 16 and 38 kDa Antigens of Mycobacterium tuberculosis as a Rapid Test for Diagnosis of Tuberculosis

Background: Serological assays for diagnosis of tuberculosis (TB) are very attractive because they are inexpensive, non invasive and simple. Present study was conducted to evaluate the tuberculosis rapid test device in Iran. Materials and Methods: The tuberculosis rapid test device based on detection of IgM, IgA and IgG antibodies against 6, 16 and 38-kDa antigens of Mycobacterium tuberculosis via chromatography was used in 96 cases of pulmonary and extra pulmonary TB. Fifty four patients with conditions other than TB were selected as the control group. Tuberculin skin test (TST) was performed in two groups. None of the patients were immunodeficient. All of them were evaluated in terms of presence of BCG scar. Results: Tuberculosis rapid test was positive in 75 cases (78.1%) and 15 controls (27.8%). This difference was statistically significant (P-value < 0.001). TST was positive in 66 patients (68.8%) with tuberculosis and 10 (18.5%) controls with no statistically significant difference (P-value = 0.065). Sensitivity, specificity, positive and negative predictive values of the tuberculosis rapid test for diagnosis of tuberculosis were 78.1%, 72.2%, 83.3% and 65%, respectively. These parameters for TST were 31.3%, 81.5%, 75%, and 40%, respectively. Conclusion: Tuberculosis rapid test has better sensitivity than TST and may be helpful in diagnosis of tuberculosis as a complementary test or in epidemiological investigations.