Evaluation of the effectiveness of BACTEC MGIT 960 for the detection of mycobacteria in Bangladesh

Abstract

Objective: Tuberculosis (TB) caused by Mycobacterium tuberculosis has been identified as a re-emerging infectious disease with public health importance globally. Exploitation of new laboratory techniques for precise identification of mycobacteria in clinical specimens is of great importance to improve the diagnosis as part of the global TB control efforts. Methods: The current study was conducted for the evaluation of BACTEC MGIT 960 method in comparison with Lowenstein–Jensen (LJ) culture and light emitting diode (LED) fluorescence microscopy for isolation of mycobacteria among TB suspects from Bangladesh. A total of 421 specimens were tested with these methods. Results: Among the tested samples, 3.6% (n = 15) were LED fluorescence microscopy positive; while 18 (4.2%) and 45 (10.6%) were recovered from LJ and MGIT 960 culture. The relative positivity found through MGIT 960 system were 60% and 66.7% higher than that of LJ culture and LED fluorescence microscopy, respectively. Recovery rate of Mycobacterium tuberculosis complex ([MTC], 21 by MGIT and 16 by LJ culture) and non-tubercular mycobacteria ([NTM], 24 by MGIT and 2 by LJ culture) by MGIT 960 was 24% and 96% greater, respectively than LJ culture. Moreover, MGIT 960 was found to be highly sensitive (100%), specific (93.3%), accurate (93.6%) and a more rapid method in detecting mycobacteria when compared with LJ culture. Conclusion: Extended recovery of NTM and MTC through MGIT 960 urged frequent application of this method to detect mycobacteria more effectively and rapidly.

Keywords

• BACTEC MGIT 960
• Lowenstein–Jensen culture
• Light emitting diode (LED) fluorescence microscopy
• Mycobacteria
• Mycobacterium tuberculosis complex (MTM)
• Non-tubercular mycobacteria (NTM)