Comporison of the bactec mgıt 960 and bactec 460tb culture systems for recovery, identification and drug susceptibility testing of mycobacterium tuberculosis

Comparison of the BACTEC MGIT 960 and BACTEC 460TB culture systems for recovery, identification and drug susceptibility testing of Mycobacterium tuberculosisIn the present study, it was aimed to compare the performances of BACTEC MGIT 960 and BACTEC 460TB culture systems in terms of isolation of M.tuberculosis complex (MTBC) from clinical specimens, identification, and anti-tuberculosis drug susceptibility testing.BACTEC MGIT 960, BACTEC 460TB and Lowenstein-Jensen (LJ) medium culture testing of totally 1066 clinical specimens, 694 respiratory and 372 non-respiratory, which enrolled in the study, yielded MTBC isolation rates of 86.5% (n = 32), 83.8% (n = 31) and 54.0% (n = 20), respectively. The mean detection times for MTBC were 13.7 (5-35) days, 14.6 (4-26) days and 20.7 (12-43) days; the contamination rates were 6.6%, 2.6% and 7.7% respectively, in the same order. In comparison of identification performances, the isolated fifty-one mycobacteria strains, 30 MTBC and 21 nontuberculous mycobacteria (NTM) were tested by using TBc ID test (BD MGIT TBc Identification Test) and the NAP test (BACTEC NAP TB Differentiation test), and consequently all were determined to be identified correctly. Drug susceptibilities of the 50 M.tuberculosis strains against streptomycine (SM), isoniazid (INH), rifampin (RIF) and ethambutol (EMB) were investigated by using both two systems. The compatibility between the susceptibility test results were determined as 82%, 100%, 100%, 96% for SM, INH, RIF and EMB, respectively.In conclusion, no statistical difference was detected in terms of the isolation of MTBC from clinical specimens and identification performances between the two systems; however, contamination rates were noted significantly higher in the BACTEC 960 system. Regarding susceptibility performance, a statistically significant difference was not observed between the two systems, except for SM.Key words: Mycobacterium tuberculosis complex, BACTEC MGIT 960, BACTEC 460TB, culture, identification.