DIAGNOSIS OF TUBERCULOSIS BY AMPLICOR MYCOBACTERIUM-TUBERCULOSIS TEST- A MULTICENTER STUDY

The Amplicor Mycobacterium tuberculosis test is a new PCR assay for th e direct detection of Mycobacterium tuberculosis from clinical samples , A multicenter study that included six laboratories was done to evalu ate the Amplicor test in comparison with direct microscopy and culture (solid or radiometric media), and the culture method was used as the ''gold standard.'' A total of 2,073 specimens, i.e., 1,749 respiratory specimens and 324 other specimens, were tested, A total of 184 cultur es yielded M. tuberculosis. Of these 184 cultures, 77 (42%) were smear negative and 23 (12.5%) concerned extrapulmonary specimens, The sensi tivity of the Amplicor test for all of the specimens and for extrapulm onary, smear-positive, and smear-negative specimens was 86, 83, 94.5, and 74%, respectively, The sensitivity of direct microscopy in compari son with that of culture was 58%. A total of 95% of patients with cult ure-proven tuberculosis were diagnosed by the Amplicor test, whereas d irect microscopy detected mycobacteria in only 72% of these patients. The Amplicor test exhibited a high degree of specificity (98%). The as say was very rapid and easy to perform.