Evaluation of the BD MGIT TBc Identification Test (TBc ID), a rapid chromatographic immunoassay for the detection of Mycobacterium tuberculosis complex from liquid culture

The BACTEC MGIT 960 system is increasingly used to culture Mycobacterium tuberculosis. We evaluated the performance of the new immunochromatographic assay BD MGIT TBc Identification Test (TBc ID) for the rapid identification of M. tuberculosis complex in clinical samples when performed directly from BACTEC MGIT 960 culture positive for acid-fast bacilli (AFB). Of 92 cultures evaluated, the sensitivity and specificity of the TBc ID test was 98.5% and 100%, respectively compared to sequencing of the 16S rRNA gene. One culture that was TBc ID test negative but that was identified as M. tuberculosis by 16S rRNA sequencing was confirmed to have a mutation in the mpt64 gene. The TBc ID test is an easy and sensitive method for the identification of M. tuberculosis complex in liquid culture medium, does not require a high level of skills, neither any additional specific equipment and gives results in 15min, which provide a good alternative for the rapid identification of M. tuberculosis complex in liquid medium.