Comparative evaluation of the BACTEC MGIT 960 system with solid medium for isolation of mycobacteria.

摘要

SETTING: The utilisation of new, rapid methods of diagnosis of tuberculosis is currently of great interest for tuberculosis control. This study was carried out in a teaching hospital in the eastern region of Taiwan. OBJECTIVE: The BACTEC MGIT 960 system was evaluated and compared with Lowenstein-Jensen (LJ) medium and Middlebrook 7H11 plate for recovery rate and time to detection of mycobacteria. DESIGN: A total of 1396 sputum samples were tested for the presence of mycobacteria. Specimens were processed and inoculated separately in the BACTEC MGIT 960 system, on LJ medium and 7H11 for comparative study. RESULTS: The BACTEC MGIT 960 detected 235 isolates (100%), followed by LJ with 205 isolates (87.2%) and 7H11 with 178 isolates (75.7%). The mean time to detection of Mycobacterium tuberculosis complex was 11.6 days with MGIT 960, 20.1 days with LJ, and 18.7 days with 7H11. The contamination rates were 15.1% with MGIT 960, 10.1% with LJ and 9.7% with 7H11. CONCLUSION: The BACTEC MGIT 960 system is a sensitive, rapid mycobacterial culturing system. However, the high contamination rate is a concern that should be carefully evaluated in the clinical setting.