WHO estimates that 30% of the world’s population is infected with the tuberculosis bacterium

Multidrug-resistant TB (MDR-TB) is caused by organisms that are resistant to isoniazid and rifampicin. MDR-TB results from either infection with organisms which are already drug-resistant or become resistant during therapy.

Extensively drug-resistant TB (XDR-TB) is a form of TB caused by organisms that are resistant to isoniazid and rifampicin or any of the second-line anti-TB injectable drugs amikacin, kanamycin or capreomycin.