Comparison of the performance of TK system with LJ and MGIT methods in the diagnosis of tuberculosis.

Tuberculosis is a common infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis (TB). Various liquid or solid media are used for the diagnosis of tuberculosis. TK Rapid Mycobacterial Culture System has been developed recently. In our study, we aimed to compare TK Rapid Mycobacterial Culture System with LJ and MGIT systems in the diagnosis of tuberculosis. 200 clinical specimens (152 sputum, 41 Bronchoalveolar lavage fluid (BAL), 4 gastric aspirations, 2 urine and 1 wound) obtained from 192 patients from different clinics were included for the diagnosis of TB. All specimens were decontaminated by using the same-common procedure in all the methods. The obtained sediment was used for inoculation for the BACTEC MGIT 960, TK and LJ. Additionally, smears were prepared from the residual suspension for Ehrlich-Ziehl-Neelsen (EZN) staining for microscopic examination. Contamination was observed in 23 sputum and 4 BAL samples. Contamination rates for TK, LJ, and BACTEC MGIT 960 systems were determined as 3 (1.5%), 13 (6.5%), and 18 (9%) respectively. Mycobacterium tuberculosis growth was determined as 15 (7.5%), 14 (7%) and 13 (6.5%) by TK culture system, MGIT and LJ, respectively. In our study, the total mean detection times of Mycobacterium tuberculosis by the LJ, TK, and MGIT method were 20.1, 17.1, and 8.3 days, respectively. TK system showed a dramatically lower contamination rate than the others. There was no difference in growth rates for each of the three methods. We concluded that the TK culture system is disadvantageous in terms of turnaround time.