Non Tuberculous Mycobacteria (NTM) are widely distributed in our environment
and man is being constantly exposed to these organisms by various means(l). This
immunologically important contact may be involved in the modulation of immunity to
tuberculosis. Prior sensitization with NTM has beep considered as one of the explanations
for the failure of BCG to provide protection against tuberculosis in the South Indian trial.
Tuberculosis surveys using PPD-B have shown that in this area, prevalence of
sensitization reaches 90%. in persons by age 14(2). Identification of NTM isolates from
sputum samples in this area has shown M.avium-intracellulare and M.scrofulaceum to be
among the important species(3). However. the actual distribution profile of the various
NTM species in the environment of this area is not known
