XDR tuberculosis (XDR-TB) refers to extensively drug-resistant tuberculosis. In addition to the drugs involved in multidrug-resistant (MDR) tuberculosis - rifampicin and isoniazid - the bacteria are resistant to other important tuberculosis drugs.

In pre-XDR tuberculosis, there is additional resistance to a fluoroquinolone, in XDR tuberculosis to a fluoroquinolone and to bedaquiline or linezolid. This means that these drugs are also ineffective. The treatment of this form of tuberculosis is more difficult compared to MDR tuberculosis and the chances of recovery are lower. In order to exhaust all treatment options, XDR tuberculosis should be treated by specialized doctors.