Comparison of the AMPLICOR MYCOBACTERIUM test with microscopy and culture for diagnosis of pulmonary tuberculosis

Tuberculosis (TB) is one of the major public health problems in Taiwan. Effective control of TB depends on rapid and correct diagnosis and appropriate treatment. The aim of this study was to evaluate the performance of the Roche AMPLICOR MYCOBACTERIUM (AMPLICOR MTB) test compared with microscopy and culture for diagnosis of pulmonary TB. A total of 123 specimens obtained from 90 suspected pulmonary TB patients were included in this study. All specimens were processed, stained, cultured and assayed using the AMPLICOR MTB test for identification of M. tuberculosis. All patients were followed up for 1 year to confirm or exclude the diagnosis of pulmonary TB. M. tuberculosis was isolated from 29 of these specimens, and final diagnosis of pulmonary TB was identified in 50 patients according to clinical discrepancies. On initial testing, the sensitivity, specificity, positive and negative predictive values of the AMPLICOR MTB test, compared with cultures, were 75.9, 84, 59.5, and 91.9%, respectively. After resolution of discrepancies by the final clinical diagnosis, the sensitivity, specificity, positive and negative predictive values were 72, 98.6, 97.3, and 83.7%, respectively. For smear-positive specimens, the sensitivity was 84.9%, for smear-negative specimens, the sensitivity was 47.1%. Our study demonstrated that the use of the AMPLICOR MTB test was highly sensitive and specific for rapid diagnosis of pulmonary TB. Further studies are needed to determine the cost-effective use of this test with smear-negative specimens.