Tuberculosis (TB) is one of the main lethal infectious diseases worldwide, with 9.6 million people affected and 1.5 million deaths, in 2014. Over 95% of TB deaths tend to occur in low- or middleincome countries (http://www.who.int/mediacentre/factsheets/fs104/ en/). In Iran, the estimated incidence of all TB types was 17,000, case detection rate was 22 (per 100,000 population), and mortality rate of TB cases (all forms, excluding in HIV positive patients) was 3.5 (per 100,000 population), in 2014 (http://who.int/tb/country/data/ profiles/en/index.html).
The disease still remains a global concern with an increasing rate due to drug-resistant TB. Globally, about 3.3% of new and 20% of formerly treated cases were diagnosed as Multi-drugresistant Tuberculosis (MDR-TB), with the rates remaining almost unchanged in recent years. In 2014, there were approximately 480,000 (range: 360,000–600,000) new cases of MDR-TB worldwide, and roughly 190,000 (range: 120,000–260,000) deaths from MDR-TB. Among patients with pulmonary TB who were diagnosed in 2014, on average 300,000 (range: 220,000–370,000) suffered from MDR-TB. More than half of these patients were from India, China, and Russia. In Iran, there was approximately 0.8% (0.30–1.4%) of new TB cases with MDR-TB in the same year.