A comparative study for the detection of Mycobacteria by BACTEC MGIT 960, Lowenstein Jensen media and direct AFB smear examination

Abstract

Purpose: To compare BACTEC MGIT 960 (M960) with conventional culture on Lowenstein Jensen (LJ) media and direct acid fast bacilli (AFB) smear examination for the detection of Mycobacteria in clinical samples obtained from suspected cases of pulmonary and extra pulmonary tuberculosis (TB).

Methods: A total of 500 samples were processed for direct AFB smear examination, and culture on M960 and LJ media.

Results: Two hundred fifty-eight out of 500 (51.6%) isolates of Mycobacteria were obtained by combined use of the two culture methods. Two hundred and fifty-three (50.6%) were positive in culture by M960 and LJ media and 28% (140/500) by direct AFB smear examination. The positivity rate of M960 system alone was 34.10% (88/258) and of LJ alone was 1.93% (5/258). Average time to detect growth (TTD) was 9.66 days by M960 and 28.81 days by LJ.

Conclusions: M960 system is a rapid and sensitive method for early diagnosis of pulmonary and extrapulmonary TB. But for maximum recovery of Mycobacteria , a combination of both M960 and LJ media should be used.