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Tuberculosis Research and Treatment
Volume 2013, Article ID 108401, 6 pages
Research Article

Evaluation of MGIT 960 System for the Second-Line Drugs Susceptibility Testing of Mycobacterium tuberculosis

1Korean Institute of Tuberculosis, 168-5, Osong sangmyung 4 ro, Osong-eup, Cheongwon-gun, Chungbuk 363-954, Republic of Korea
2Novartis Korea LTD, CD&MA, Namdaemunro 5-ga, Joon-gu 100-753, Republic of Korea
3Centers for Infectious Diseases, National Institute of Health, Korea Centers for Disease Control and Prevention, 187 Osong sangmyung 2 ro, Osong-eup, Cheongwon-gun, Chungbuk 363-951, Republic of Korea

Received 24 December 2012; Revised 7 March 2013; Accepted 11 March 2013

Academic Editor: Alexander S. Apt

Copyright © 2013 Hyejin Kim et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Many laboratories validate DST of the second-line drugs by BACTEC MGIT 960 system. The objective of this study is to evaluate the critical concentration and perform DST for the 2nd line drugs. We evaluated 193 clinical strains of M. tuberculosis isolated from patients in South Korea. Testing the critical concentration of six second-line drugs was performed by MGIT 960 and compared with L-J proportion method. The critical concentration was determined to establish the most one that gave the difference between drug resistance and susceptibility in MGIT960 system. Good agreement of the following concentrations was found: Concordance was 95% for 0.5 μg/mL of moxifloxacin; 93.6%, 1.0 μg/mL of levofloxacin; 97.5%, 2.5 μg/mL of kanamycin; 90.6%, 2.5 μg/mL of capreomycin; 86.2%, 5.0 μg/mL of ethionamide; and 90.8%, 2.0 μg/mL of -aminosalicylic acid. The critical concentrations of the four drugs, moxifloxacin, levofloxacin, kanamycin, and capreomycin, were concordant and reliable for testing 2nd line drug resistance. Further study of ethionamide and ρ-aminosalicylic acid is required.