SEROLOGY VERSUS SPUTUM MICROSCOPY AFTER THE INTENSIVE PHASE OF DOTS THERAPY: EVALUATION OF A MPT64 BASED ASSAY

Fast, sensitive, specific yet inexpensive methods for detection of tuberculosis remain elusive. In spite of its limitations sputum smear microscopy remains the most widely used method for it’s detection. Various commercial antigen based serological tests are being promoted as an alternative to sputum microscopy. These tests offer an economically viable pragmatic alternative to smear microscopy. Few studies exist evaluating the performance of serological tests after the intensive phase of DOTS. We believe to be an effective alternative to sputum microscopy; serology must perform reasonably well in all the stages of therapy. We evaluated the sensitivity and specificity of a single serological test after two months of intensive phase drug therapy in previously seropositive and smear positive patients attending the DOTS clinic of a tertiary care hospital. Our results showed a sensitivity of 0.5 (0.17-0.82 95% CI) and a specificity of 0.25 (0.11-0.46 95% CI) taking sputum smear microscopy as the gold standard. We concluded that the present formats of serological tests are not useful in differentiating an active infection from a recently cured infection. Further research must be done on detecting antibodies which reflect the true infection load.