A comparison of the BACTEC radiometric method with the conventional culture and drug
susceptibility testing methods on isolates from clinical specimens in pulmonary and extrapulmonary
tuberculosis, childhood TB and TB in HIV-infected individuals was undertaken. In the case of
pulmonary TB, the rate of isolation of positive cultures was significantly faster with the BACTEC
method, with 87 per cent of the positives being obtained by 7 days, and 96 per cent by 14 days.
However, while there was no difference in the total number of positive cultures by the two methods
in smear positive pulmonary tuberculosis, in smear negative pulmonary TB, the BACTEC method
yielded more number of positive cultures. In extrapulmonary TB, HIV-TB and childhood TB,
although the BACTEC method did not yield additional positives, the detection of positives was
considerably faster than by the conventional methods, in which the degree of growth was also scanty.
The agreement in drug susceptibility tests was 94 per cent for streptomycin and isoniazid, 99 per cent
for rifampicin and 91 per cent for ethambutol. Further, most of the drug susceptibility test results
became available within 8 days by the BACTEC method. By facilitating early diagnosis, the BACTEC
method may prove to be cost effective in a population with a high prevalence of tuberculosis,
particularly in the extrapulmonary and paucibacillary forms of the disease