Source of Support: None, Conflict of Interest: None
Out of a total of 4943 patients admitted to various chemotherapy studies at the Tuberculosis Research Centre, Madras, India, over the past two decades. 21 were found to be repeatedly excreting mycobacteria other than the typical human tubercle becilli, thus giving a low detection rate of 0.4%. The persistant isolation of atypical or non-tuberculous or unclassified mycobacteria (UMB) on repeat cultures, supported by laboratory identification tests confirmed the pathogenic nature of the organisms causing pulmonary disease. Chest radiographic appearances were similar to those infections caused by typical tubercle bacilli. Thirteen of 21 patients yielded repeat isolates identified as Photochromogens by special invitro tests, especially those patients who had not previously had tuberculosis. The remaining patients were positive for non-chromogens. This report presents a retrospective analysis on 21 such patients. Occupational exposure to dust was common. Follow up studies indicated radiographic improvement in nine patients and a bacteriological negative status in 11. Ten patients died. The antituberculosis drug regimens were variable, but response was considered unsatisfactory in nearly 50% of patients.