부산대학교 도서관

Lowenstein-Jensen (L-J) medium is commonly used for culturing mycobacteria. For detection of mycobacteria in sputum specimens, laboratories in Taiwan usually use Mycobacteria Growth Indicator Tubes (MGIT) coupled with the BACTEC MGIT 960 system and L-J medium. This study investigated the growth behavior of Mycobacterium spp. on L-J medium and MGIT. Of the 89,197 sputum samples collected from April 2016 to December 2017, 9,547 showed growth of mycobacteria on these media with three different growth patterns: (i) MGIT (+), LJ (-); (ii) MGIT (+), LJ (+) and (iii) MGIT (-), LJ (+). Sample proportions of these 3 growth patterns were 59.1% (5,638), 33.9% (3,234), and 7.1% (675), respectively. This result indicated that various Mycobacterium spp. grew differently on these media. Among all mycobacterial isolates investigated in this study, 59.1% of them did not grow on L-J medium, and 7.1% of them did not grow on MGIT. The top 3 most abundant MGIT (+), L-J (-) isolates were Mycobacterium avium complex (MAC) (29.9%), M. tuberculosis complex (MTBC) (23.6%), and M. abscessus complex (12.5%). MTBC (36.9%), M. fortuitum (15.3%) and M. abscessus complex (14.2%) were the 3 most abundant MGIT (+), LJ (+) isolates , and the top 3 most abundant MGIT (-), LJ (+) isolates were M. gordonae (39.7%), MAC (11.1%), and M. fortuitum (10.1%). Among the MGIT (-) isolates, M. gordonae (often considered as water-borne bacteria) was predominant, and MTBC accounted for 6.8% (46/675) of this population. Based on results of this study, we concluded that L-J medium and MGIT have different sensitivity in the detection of mycobacteria. Therefore, both culture media should be used simultaneously for detection of mycobacteria. If necessary, additional selective media such as Middlebrook 7H11 agar should be used. Molecular and immunological methods may also be required to ensure successful detection of mycobacteria in sputum specimens.