Epidemiology of multidrug-resistant tuberculosis.

Since the nineties, the increasing incidence of tuberculosis was accompanied by numerous epidemic foci of multidrug-resistant strains of Mycobacterium tuberculosis, especially of nosocomial transmission. In the United States and other countries there was an increase in both primary and acquired drug-resistant tuberculosis. HIV infection and the poor social and health care facilities of different population groups, the lack of compliance with therapy and the reduction of programs of nosocomial and extranosocomial surveillance and control of tuberculosis are all concomitant causes of the increase in multi-drug resistant cases. The improvement in surveillance and treatment closely monitored therapies and nosocomial control by specific regulations, when applied, have contributed to the decrease in the rate of drug-resistant forms.