Detection of Mycobacterium tuberculosis from respiratory samples with the liquid culture system MB/BacT and verified by PCR

Abstract

Objective: To assess the performance in the clinical setting of the MB/BacT system for isolation of Mycobacterium tuberculosis and to verify by PCR.

Material and methods: The study included 272 sputum samples from 208 patients with the presumptive diagnosis of pulmonary tuberculosis. ZN was made, culture in Löwenstein-Jensen medium, MB/BacT and PCR.

Results: Thirty-nine samples were positive by culture in Löwenstein-Jensen, and 42 using the MB/BacT system. Positive cultures in the MB/BacT system were verified by acid-fast bacilli staining and PCR. Mycobacterial identification in the MB/BacT took 8 to 46 days (mean 16 days), while the Löwenstein-Jensen culture ranged between 21 and 63 days (mean 35 days). These results show that the MB/BacT semiautomated system is reliable and faster than the manual culture method and can be used as an alternative for the primary identification of Mycobacterium tuberculosis. The PCR assay allows the fast and exact identification of Mycobacterium tuberculosis directly from positive liquid medium.