Annals of Clinical Microbiology, The official Journal of the Korean Society of Clinical Microbiology

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pISSN 2288-0585 eISSN 2288-6850

Evaluation of Mycobacteria Growth Indicator Tube for Drug Susceptibility Testing of Mycobacterium tuberculosis Using MGIT 960 System

Original article

Annals of Clinical Microbiology (Ann Clin Microbiol) 2002 June Volume 5, Issue 1, pages 47-51.

Evaluation of Mycobacteria Growth Indicator Tube for Drug Susceptibility Testing of Mycobacterium tuberculosis Using MGIT 960 System

Youn Mi Choi

Department of Clinical Pathology, Seoul Veterans Hospital, Seoul, Korea

Abstract

Background:Multidrug resistant tuberculosis (MDRTB) strains rely on the prompt availability of drug susceptibility test results. We evaluated the reliability and turnaround time of MGIT 960 system, automated version of the MGIT, for antimicrobial susceptibility test of Mycobacteria tuberculosis.

Methods:Ninety six isolates have been tested for susceptibility to isoniazid (INH), rifampin (RIF), ethambutol (EMB) and streptomycin (SM). Results were compared with those obtained by traditional solid media (absolute concentration method, indirect method).

Results:There was no statistically significant difference between the susceptibility testing results of the two methods except for EMB. Discrepant results were obtained for 8 isolates (8.3%) with INH, for 3 isolates (3.1%) with RIF, for 13 isolates (13.5%) with EMB, for 10 isolates (10.4%) with SM. Using the indirect method as the gold standard, the sensitivity of INH, RIF, EMB and SM susceptibility testing by the MGIT system were 94.1%, 98.8%, 86.7% and 90.0%, respectively. The specificity were 85.7%, for INH and RIF and 83.3%, for EMB and SM. Turnaround times were significant shorter in MGIT (average 12 days) than in solid media (average 57 days) (P < 0.05)

Conclusions:These data demonstrate that the MGIT system is accurate and rapid for INH, RIF and SM susceptibility test of M. tuberculosis, but EMB susceptibility testing requires further evaluation. (Korean J Clin Microbiol 2002;5(1):47-51)

Keywords

Mycobacterium tuberculosis, Mycobacterium growth indicator tube, Antimicrobial susceptibility testing