Evaluation of a rapid assay for identification of Mycobacterium tuberculosis grown in solid and liquid media

An MPT64 antigen detection assay, the SD Bioline TB Ag MPT64 Rapid kit, was evaluated for the identification of Mycobacterium tuberculosis grown in both solid and liquid media. The rapid test showed positive results in 132 of 133 (99.2%) M. tuberculosis cultures grown on Ogawa medium and 136/143 (95.1%) cultures grown in liquid culture medium, resulting in an overall sensitivity of 97.1%. All 18 non-tuberculous mycobacteria were found to be negative by the rapid test, indicating a specificity of 100%. The rapid test seems useful for the initial confirmation of M. tuberculosis in acidfast bacilli positive cultures.