Zürcher K, et al. - Via performing a multicentre cohort study in Côte d'Ivoire, Democratic Republic of the Congo, Kenya, Nigeria, South Africa, Peru, and Thailand, researchers determined mortality in patients with tuberculosis from these high-burden countries, according to concordance or discordance of results from drug susceptibility testing done locally and in a reference laboratory. They analyzed 634 patients with tuberculosis; the median age was 33·2 years, 239 (38%) were women, 272 (43%) were HIV-positive, and 69 (11%) patients died. The reference laboratory drug susceptibility test indicated that 394 (62%) strains were pan-susceptible, 45 (7%) monoresistant, 163 (26%) multidrug-resistant (MDR), and 30 (5%) had pre-extensively or extensively drug resistant (pre-XDR or XDR) tuberculosis. For 513 (81%) of 634 patients, results of reference and local laboratories were concordant and for 121 (19%) of 634, the results were discordant. Under-treatment of drug-resistant tuberculosis and increased mortality were noted in correlation with inaccurate drug susceptibility testing by comparison with a reference standard. They suggest improving outcomes in patients with MDR tuberculosis and pre-XDR or XDR tuberculosis by rapid molecular drug susceptibility test of first-line and second-line drugs at diagnosis.