Comparison of MB/BacT and BACTEC 460 TB Systems for Recovery of Mycobacteria in a Routine Diagnostic Laboratory

MB/BacT, BACTEC 460 TB, and Löwenstein-Jensen (LJ) medium were evaluated in parallel for recovery of mycobacteria from 3,700 continuous clinical specimens in a routine laboratory. Mycobacteria were identified from 123 (3.3%) specimens. The recovery rates for all mycobacteria by the different systems were 91.0, 73.0, and 53.6% for BACTEC 460 TB, MB/BacT, and LJ medium, respectively. The recovery rates for Mycobacterium tuberculosis complex were 97.1, 80.2, and 67.6%, respectively. The lack of sensitivity of the MB/BacT system was more pronounced with smear-negative specimens and resulted in a failure to detect three patients with infectious tuberculosis.