[Antimicrobial susceptibility testing for Mycobacterium tuberculosis by measuring mycobacterial adenosine...

The antimicrobial susceptibility test for Mycobacterium tuberculosis H37Rv and 43 clinical isolates was performed using a bioluminescence assay by measuring the content of adenosine triphosphate (ATP) derived from mycobacteria. The drugs tested were isoniazid (INH), rifampicin (RFP), ethambutol (EB), streptomycin (SM), and kanamycin (KM). The ATP contents of M. tuberculosis incubated in the Middle-brook 7H9 broth medium containing antituberculous agents were measured at days of 0, 1, 3, 5, 7 and 10. A reduction of ATP content, indicating growth inhibition, was observed in susceptible strains within 5 to 10 days of incubation. Optimal concentrations to distinguish between susceptible and resistant strains were determined as being INH 0.20, RFP 0.50, EB 5.0, SM 4.0, KM 6.0 g/ml. The agreements of ATP method (evaluated at 10 days) with Vite Spectrum and MIC determinations were 81.4% and 100%, respectively. Susceptibilities to most drugs, except for EB, could be determined within 7 days. This method is simple, rapid, nonradiometric, and can be used for drug susceptibility.