The reason AFB or TB culture is recommended is to confirm the diagnosis of TB, since other mycobacteria (non-tuberculous or atypical mycobacteria) can also mimic TB and are positive for AFB on microscopy. Secondly, the culture test can be followed by susceptibility testing, which is very useful, since many cases are now multi-drug resistant, and the drugs susceptibility results can be used to modify the treatment and make it more specific for the patient.
This test would be available at government medical colleges as well big TB centres.