Tuberculosis remains the world's leading infectious cause of adult deaths, most of which are due not to multidrug resistant tuberculosis but to lack of access to effective treatment for drug susceptible tuberculous disease.1 New data suggest, however, that multidrug resistant tuberculosis is emerging as an increasingly important cause of morbidity and death. In the United States, Europe, and Latin America, highly resistant strains of tuberculosis have caused explosive institutional outbreaks (in hospitals, prisons, and homeless shelters) with high case fatality rates among immunosuppressed people and high rates of transmission to other patients and to caregivers and their families.2^–8

These outbreaks are not restricted to certain regions. The WHO/International Union Against Tuberculosis and Lung Disease's global survey of resistance to antituberculous drugs now reveals that multidrug resistant tuberculosis has already become established worldwide. In several countries—including Russia, Estonia, Latvia, Côte d'Ivoire, and the Dominican Republic—“hot zones” of ongoing transmission have been identified. Failure to follow the World Health Organisation's guidelines was clearly associated with high rates of multidrug resistant tuberculosis; the survey was thus able to identify countries in which an increase in multidrug resistant tuberculosis was likely, given the current programme conditions.9

Unfortunately, treatment options have been limited for most people with multidrug resistant tuberculosis, largely because of the cost of drugs. …