Evaluation of the MB/BacT System for recovery of mycobacteria from clinical specimens in comparison to Lowenstein-Jensen medium

AbstractObjective To evaluate the performance of the MB/BacT system (Organon Teknika) in comparison to Lowenstein-Jensen (LJ) solid medium for recovery of mycobacteria from clinical specimens.Methods Two thousand three hundred and ten specimens (1626 respiratory, 593 urine, 60 body fluids, five tissue and 26 others) were inoculated in MB/BacT (0.5 mL) and on two LJ slants (0.25 mL each). N-acetyl-l-cysteine-NaOH (final concentration 2%) was used for decontamination.Results Two hundred and fifty-one (10.8%) mycobacterial isolates [190 Mycobacterium tuberculosis complex (MTBC) and 61 non-tuberculous mycobacteria (NTM)] were detected. Of these 251 isolates, 234 (93.2%; 181 MTBC and 53 NTM) were detected in MB/BacT and 169 (67.3%; 154 MTBC and 15 NTM) on LJ. The mean (median) times to detection of MTBC by MB/BacT and LJ were 13.8 (13) and 22.1 (20) days, respectively, while overall contamination rates were 7.7% and 8.1%, respectively.Conclusions Sensitivity and time to detection were significantly better with MB/BacT than with solid LJ medium