Evaluation of effectiveness of manual MGIT system for detection of Mycobacterium

Objective To evaluate the value of MGIT liquid medium with manual fluorescence instrument for rapid detection of Mycobacterium. Methods During March-April 2011, 230 specimens from newly diagnosed and re-treated TB patients were collected in Hangzhou Red Cross Hospital, in which 57 specimens were positive and 173 were negative by acid-fast stain (AFB) microscopic examination. Mycobacterium in the same specimens was isolated with L-J and MGIT liquid medium respectively. The data were analyzed statistically with 2 and Z test, the Results were statistical significant (P0.05). Results Among 230 sputum specimens, 90 Mycobacterium stains (39.1%) were cultivated by both MGIT and L-J medium, 79 (34.3%) by MGIT and 63 (27.4%) by L-J medium, respectively. Of 173 AFB smear-negative specimens, 33 (19.1%) were cultured by MGIT, while 19 (11.0%) were cultured by L-J medium. The positive rate of culture with MGIT was significantly higher than that with L-J medium (P0.05). The mean time of Mycobacterium detection with MGIT was 13 days, while that with L-J medium was 21 days, the difference was significant (Z=3.293, P0.001). On the average time of obtaining positive results, it was 7 days earlier for AFB smear-positive samples than for AFB smear-negative samples with MGIT. Conclusion Manual MIGT liquid medium method is rapid in detecting Mycobacterium with high positive rate, which is suitable for the routine diagnosis in laboratories at grass roots level.