SENSITIVITY OF AMPLICOR MTB ON DIRECT DETECTION OF MYCOBACTERIUM TUBERCULOSIS IN SMEAR-NEGATIVE SPECIMENS FROM OUTPATIENTS IN RIO DE JANEIRO

We evaluated the performance of the AMPLICOR MTB assay for detection of M. tuberculosis in clinical specimens obtained from 98 smear-negative tuberculous patients (43 with positive and 55 with negative culture results). The sensitivity of the AMPLICOR MTB was 44.9 % (44/98) and that of culture was 43.8 % (43/ 98). No significant difference was observed between the results obtained by AMPLICOR MTB and by culture. We conclude that amplification assays could be used for testing smear-negative specimens because a rapid diagnosis will benefit those patients. Key words: tuberculosis, AMPLICOR MTB, smear-negative specimens. Laboratory diagnosis of tuberculosis (TB) currently depends on acid-fast staining and culture of clinical specimens. Microscopic examination of acid-fast smears is not very sensitive, and culture is very specific but usually requires two to three weeks of incubation. Over the last five years several studies evaluated commercial amplification kits designed to directly detect Mycobacterium tuberculosis DNA and RNA i