Rapid diagnosis of tuberculosis and multidrug resistance using a MGIT 960 system

Background: The purpose of this study was to compare the turnaround time for liquid culturing and primary anti-tuberculous drug susceptibility testing (DST) performed using the mycobacteria growth indicator tube (MGIT) 960 system (Becton Dickinson, USA) with that for conventional culturing and DST (by the absolute concentration method) performed using solid culture medium and to determine the concordance rates of DST results obtained using these 2 methods. Methods: In this retrospective study, we compared the turnaround times from receiving the request for mycobacterial culture to reporting the DST results before and after the introduction of the MGIT 960 system. Further, we determined the concordance between DST results for isoniazid and rifampin for Mycobacterium tuberculosis isolates obtained using the MGIT 960 system and the absolute concentration method, which was conducted at the Korean Institute of Tuberculosis. Results: The overall turnaround time for mycobacterial culturing and DST was 27 days for liquid culturing and DST using the MGIT 960 system versus approximately 70 days for culturing on solid medium and DST with the absolute concentration method (P<0.001). There was a good concordance between fndings of DST obtained with the 2 methods (97.2%, kappa coeffcient=0.855 for rifampin; and 95.6%, kappa coeffcient=0.864 for isoniazid), for 1,083 clinical isolates. Conclusions: The automated MGIT 960 system for culturing and DST of M. tuberculosis was successfully introduced in a hospital laboratory setting in Korea with signifcant shortening of the turnaround time.