OBJECTIVE: To compare the accuracy of the amplified Mycobacterium
tuberculosis direct (AMTD) test with reference methods for the
laboratory diagnosis of tuberculosis in HIV-infected patients. METHODS: This was a study of diagnostic accuracy comparing AMTD test results with those
obtained by culture on Löwenstein-Jensen (LJ) medium and by the BACTEC
Mycobacteria Growth Indicator Tube 960 (BACTEC MGIT 960) system in respiratory
samples analyzed at the Bioassay and Bacteriology Laboratory of the Oswaldo Cruz
Foundation Evandro Chagas Clinical Research Institute in the city of Rio de
Janeiro, Brazil. RESULTS: We analyzed respiratory samples collected from 118 patients, of whom 88 (74.4%)
were male. The mean age was 36.6 ± 10.6 years. Using the AMTD test, the BACTEC
MGIT 960 system, and LJ culture, we identified M. tuberculosis
complex in 31.0%, 29.7%, and 27.1% of the samples, respectively. In comparison
with LJ culture, the AMTD test had a sensitivity, specificity, positive predictive
value, and negative predictive value of 87.5%, 89.4%, 75.7%, and 95.0%,
respectively, for LJ culture, whereas, in comparison with the BACTEC MGIT 960
system, it showed values of 88.6%, 92.4%, 83.8%, and 94.8%, respectively. CONCLUSIONS: The AMTD test showed good sensitivity and specificity in the population studied,
enabling the laboratory detection of M. tuberculosis complex in
paucibacillary respiratory specimens.