Rapid preliminary differentiation of species within the Mycobacterium tuberculosis complex: proposition of a radiometric method.

A radiometric method using the "Bactec 460-TB" apparatus now enables rapid obtaining of drug-susceptibility data and differentiation of clinical mycobacterial specimens into those belonging to the Mycobacterium tuberculosis complex (comprised of M. tuberculosis, M. bovis, M. bovis BCG and M. africanum) and non-tuberculous mycobacteria, using a specific inhibitor (p-nitro-alpha-acetyl-amino-beta-hydroxypropiophenone). In the present work, further differentiation of the M. tuberculosis complex into 4 individual species was achieved using the susceptibility of strains to 1.25 micrograms/ml of thiophene-2-carboxylic acid hydrazide, 40 micrograms/ml of D-cycloserine, and 100 micrograms/ml of pyrazinamide.