Identification of tubercle bacilli from Indian patients with pulmonary tuberculosis.

Pretreatment cultures of bacilli from Indian patients with active pulmonary tuberculosis admitted to a controlled domiciliary chemotherapy study by the Tuberculosis Chemotherapy Centre, Madras, were subjected to a series of in vitro tests designed to identify the bacilli as human or bovine tubercle bacilli, or as anonymous mycobacteria. For the purposes of comparison, pretreatment cultures from British patients with pulmonary tuberculosis were examined by the same series of identification tests.Cultures identifiable as mammalian tubercle bacilli were obtained from all the 341 Indian patients admitted to the chemotherapy study. Tests for niacin production were carried out on the cultures from 277 of these patients; all gave positive results, indicating that the bacilli in question were Mycobacterium tuberculosis var. hominis. The cultures from the Indian patients yielded results similar to those of the cultures from the British patients in all the in vitro tests except the thiacetazone-sensitivity test. In this test the Indian cultures differed from the British cultures, being on the average less sensitive and showing greater variation in sensitivity among themselves.