[Characteristics of qualitative changes in the Mycobacteria population during the treatment of middle-aged and elderly patients with newly detected pulmonary tuberculosis].

Clinicobacteriological investigations were applied to 142 new cases of pulmonary tuberculosis at the age of 60 to 89 years. The control group consisted of 132 patients of young and middle ages (from 17 to 40 years). The form of the process, its extent and the character of the destructions in them were the same as those in the elderly and senile patients. It was shown that the pathogen bacterial forms in the elderly and senile patients were much more frequent than L-forms of M. tuberculosis (67.6 and 42.9 per cent, respectively). The tubercle bacilli were mainly isolated from pure cultures (45.8 per cent). L-transformants of M. tuberculosis in the elderly and senile patients were markedly less frequent than in the patients of the control group (69.7 per cent) with analogous forms of tuberculosis. The frequency of L-forms and their rapid reversion into the initial bacterial form of M. tuberculosis (28.0 per cent) and the same period of isolating both the bacterial and L-forms were the distinctive features of the L-forms isolated from the elderly and senile patients. It was suggested that L-forms of M. tuberculosis played an important role in reactivation of the specific process.