Two hundred thirty respiratory specimens from 230 patients were analyzed by using COBAS AMPLICOR PCR, Amplified Mycobacterium tuberculosis Direct Test, and ligase chain reaction methods. Results were compared with those of smear microscopy and radiometric culture (Bactec) methods. No significant differences were observed among the results of the three methods, which are acceptable for direct detection of M. tuberculosis complex in respiratory specimens.

The BD ProbeTec ET system for identification of Mycobacterium tuberculosis complex (MTBC) isolates from BACTEC 12B culture vials was evaluated in comparison with BACTEC NAP (p-nitro-AE-acetylamino-â-hydroxy-propiophenone) differentiation. Of 145 mycobacterial isolates tested, comprising 89 MTBC and 56 non-tuberculous mycobacteria (NTM), BD ProbeTec ET correctly identified 87 MTBC and 56 NTM but missed two MTBC. Three NTM were misidentified when NAP was incubated at 37 8C only. Overall sensitivity, specificity and positive and negative predictive values were respectively 97 . 8, 100, 100 and 96 . 6 % for the BD ProbeTec ET system and 100, 94 . 6, 96 . 7 and 94 . 6 % for NAP.