Comparison of Mycobacterial Culture by Mycobacterium Growth Indicator Tube and Ogawa Media

Joung, Ue Suk; Jeong, Joseph; Lee, Seon Ho; Kim, Sung Ryul

Abstract

BACKGROUND: Mycobacterial disease is still greatly concerned in the developing and industrialized countries. Ogawa media has been used to diagnose mycobacterial disease in Korea in spite of a low sensitivity and long incubation time. Mycobacterium Growth Indicator Tube (MGIT) 960 system has been developed to overcome the pitfalls of Ogawa media. So, we investigated improvement in dectection rate and the detection time of mycobacteria using the MGIT 960 system along with 3% Ogawa media.
METHODS
A total of 8,045 clinical specimens referred to the department of laboratory medicine in Ulsan University Hospital from January in 2001 to June in 2002 were cultured for mycobacteria. Specimens were processed with the NALC-NAOH (final concentration of NaOH: 1%) and inoculated into both MGIT and Ogawa media. Mycolic acid in the cultured products were analyzed by High performance liquid chromatography to discriminate between Mycobacterium tuberculosis and nontuberculous mycobacteria.
RESULTS
Of 8,045 clinical specimens cultured, mycobacteria grew in 957 (11.9%) specimens, 840 (87.8%) M. tuberculosis and 117 (12.2%) nontuberculous mycobacteria. Mycobacteria were detected in 939 specimens (98.1%) by MGIT and 771 (80.6%) specimens by Ogawa media; 753 (78.7%) were detected by both media, 186 (19.4%) by MGIT only, and 18 (1.9%) by Ogawa media only. Mycobacteria were detected in 11.7 days by MGIT 960 and 28.4 days by Ogawa media.
CONCLUSIONS
The detection rate and detection time of mycobacteri are improved considerably by the MGIT system; however a combined use of MGIT system and Ogawa media is the most ideally recommended for increasing the detection rate and shortening the detection time.