Classification of drugs to treat multidrug-resistant tuberculosis (MDR-TB): evidence and perspectives

Multidrug-resistant (MDR) tuberculosis (TB) (defined as resistance to at least isoniazid and rifampicin), has a relevant epidemiological impact, with 480, 000 cases and 190,000 deaths notified in 2014; 10% of them meet the criteria for extensively drug-resistant (XDR)-TB [MDR-TB with additional resistance to any fluoroquinolone, and to at least one injectable second-line drugs (SLDs)] (capreomycin, kanamycin or amikacin) (1,2).