Simple and rapid identification of the Mycobacterium tuberculosis complex by immunochromatographic assay using anti-MPB64 monoclonal antibodies.

A newly developed immunochromatographic assay (MPB64-ICA) for identification of the Mycobacterium tuberculosis complex was evaluated with 20 reference strains of mycobacterial species and 111 clinical isolates. MPB64-ICA displayed a very strong reaction band with organisms belonging to the M. tuberculosis complex but not with mycobacteria other than M. tuberculosis (MOTT bacilli), except for one of four M. marinum strains tested and one M. flavescens strain, both of which gave very weak signals. The effectiveness of MPB64-ICA in combination with two liquid culture systems (MB-REDOX and MGIT) was tested. A total of 108 of 362 sputum specimens processed were positive for acid-fast bacilli. Samples taken from the cultures on the same days when either of the two culture systems became positive for mycobacteria were assayed with MPB64-ICA. Of 108 cultures with mycobacteria, 51 showed a positive signal with the test, in which the presence of the M. tuberculosis complex was demonstrated later by the Accuprobe for M. tuberculosis complex. In addition, MPB64-ICA could correctly detect the M. tuberculosis complex in mixed cultures of the M. tuberculosis complex and MOTT bacilli. These results indicate that MPB64-ICA can be easily used for rapid identification of the M. tuberculosis complex in combination with culture systems based on liquid media without any technical complexity in clinical laboratories.