CLINICAL EFFICACY OF THE AMPLIFIED MYCOBACTERIUM-TUBERCULOSIS DIRECT TEST FOR THE DIAGNOSIS OF PULMONARY TUBERCULOSIS

The amplified Mycobacterium tuberculosis direct test (MTD) is a rapid diagnostic test based on a nucleic acid amplification technique, which can be used directly on processed clinical specimens. We evaluated th e clinical utility of the MTD for diagnosing pulmonary tuberculosis by comparing the sensitivity and specificity of the test with acid-fast smear, mycobacterial culture, and clinical evaluation. The study inclu ded 844 respiratory tract specimens from 421 patients, which were subm itted to the microbiology laboratory of our urban teaching hospital ov er a 6-mo period. Compared with culture, MTD had a sensitivity of 93.6 % and a specificity of 97.8%. MTD was more sensitive in detecting pulm onary tuberculosis in patients with previously undiagnosed disease (74 .7%) than in those with established disease receiving chemotherapy (29 .2%), and in smear-positive (95.5%) than in smear-negative (70.0%) dis ease. There were two false positive MTD results in patients with nontu berculous mycobacteria, for a specificity in this population of 97.3%. We conclude that MTD, when used in conjunction with routine smear and culture, is a useful rapid diagnostic test for suspected pulmonary tu berculosis.