Improved detection and differentiation of mycobacteria with combination ofMycobacterium Growth Indicator Tube and Roche COBAS AMPLICOR system in conjunction with duplex PCR

In this study, a combination of liquid and solid media (current "gold stand ard" for culture) with combinations of liquid media (Mycobacteria Growth In dicator Tube (MGIT)) plus a commercial amplification system (Roche COBAS AM PLICOR System (CAS)), and solid media (Ogawa) plus CAS for detection of Myc obacterium tuberculosis were compared. In addition, the ability of the MGIT to recover mycobacteria from various clinical samples was compared with th e abilities of egg-based Ogawa medium using equal volume of samples and a h igh concentration (6%) of NaOH for decontamination, A total of 705 specimen s (395 respiratory and 310 extrapulmonary) that were collected from 554 pat ients were tested in parallel with three assays. The results of MGIT and Og awa were evaluated with the "gold standard" (combination of culture and cli nical data) and those of CAS were evaluated with extended gold standard inc luding treated tuberculosis. A total of 130 mycobacterial infections (M. tu berculosis, n = 122; mycobacterium other than tuberculosis (MOTT), n = 8) w ere detected. The differentiation of M. tuberculosis and MOTT was successfu lly accomplished using duplex PCR. The overall sensitivity of the MGIT, Oga wa, and CAS for M. tuberculosis was 89.9%, 73,9%, and 79.9%, respectively. For the MOTT, the corresponding values for the MGIT and Ogawa medium were 1 00% and 12.5%, respectively. The mean detection time for M. tuberculosis wa s 22 days using MGIT and 32 days when using the Ogawa medium. The specifici ty of CAS was 98.4%, with an inhibition rate of 1.4%. A combination of MGIT plus CAS detected 97.5% of all M. tuberculosis infections (compared with M GIT plus Ogawa, 91.8%, P < 0.05; compared with Ogawa plus GAS, 87.7%. P < 0 ,01). Our results indicate that a combination of MGIT plus a Roche CAS in c onjunction with duplex PCR, would be quite useful in clinical laboratories for both rapid detection and differentiation of M. tuberculosis and MOTT. ( C) 2001 Elsevier Science B.V. Ail rights reserved.