Assessment of the Mycobacteria Growth Indicator Tube for the bacteriological diagnosis of tuberculosis.

Fast, accurate diagnosis is necessary for rapid treatment of patients and to prevent the spread of Mycobacterium tuberculosis strains. The rate of recovery, mean time to detection and contamination rates of the Mycobacteria Growth Indicator Tube (MGIT) were compared with Lowenstein-Jensen (LJ) medium for mycobacterial cultures performed on 405 clinical specimens decontaminated by the trisodium phosphate method without benzalkonium chloride. The recovery rate of M. tuberculosis using MGIT was 45/61 (73.8%) compared with the reference LJ. The mean times to detection of M. tuberculosis in smear-positive specimens were 11.9 days with MGIT and 20 days with LJ. For smear-negative samples, the mean times were respectively 18.6 and 31 days, and the contamination rates were respectively 4% and 1.2%. When the trisodium phosphate decontamination method is used, MGIT cannot be used alone for isolation of mycobacteria, but may be used in combination with LJ.