DETECTION AND IDENTIFICATION OF MYCOBACTERIUM-TUBERCULOSIS DIRECTLY FROM SPUTUM SEDIMENTS BY AMPLIFICATION OF RIBOSOMAL-RNA

Seven hundred fifty-eight processed sputum sediments received for the diagnosis of tuberculosis or other mycobacterial infections were teste d by utilizing a rRNA target amplification assay and traditional cultu re techniques. The results from the rRNA target amplification assay (G en-Probe Amplified Mycobacterium Tuberculosis Direct Test), available in 5 h, were compared with the results from standard culture technique s held for 6 weeks. A total of 119 specimens (16%) were culture positi ve for Mycobacterium tuberculosis. Overall sensitivity, specificity, p ositive predictive value, and negative predictive value were 82, 99, 9 7, and 96%, respectively, for the Gen-Probe assay; 88, 100, 100, and 9 7%, respectively, for culture; and 53, 99.8, 99.6, and 91%, respective ly, for fluorochrome stain. The Gen-Probe assay employs the isothermal enzymatic amplification of M. tuberculosis complex rRNA followed by d etection of the amplicon with an acridinium ester-labeled DNA probe. T his assay has the potential of reducing the time for diagnosis of tube rculosis to 1 day.