An evaluation of the recovery of mycobacteria from urine specimens using the automated Mycobacteria Growth Indicator Tube system (BACTEC MGIT 960)

The Mycobacteria Growth Indicator Tube (MGIT 960) system was evaluated against Lowenstein-Jensen (LJ) medium and the BACTEC 460 TB system for the recovery of mycobacteria from 1393 consecutive urine specimens. The MGIT had a sensitivity of 91.3% [95% confidence interval (CI), 83.2-99.4] when the combination of BACTEC 460 and LJ medium was used as the reference method. The mean time for positivity for MGIT and BACTEC 460 was 19.3 days and 20 days, respectively, while that for LJ medium was 35 days. The incidence of contamination was highest for U medium (n=148), followed by MGIT 960 (n=81), and BACTEC 460 had the lowest incidence of contamination (n=50). In conclusion, the isolation of mycobacteria from urine specimens by the MGIT 960 is comparable to that of the BACTEC 460 TB system and solid media.