Association of drug susceptibility testing results for first- and second-line drugs with treatment outcomes in patients with multidrug-resistant and extensively drug-resistant tuberculosis.

TO THE EDITOR—We read the metaanalysis by Bastos et al recently published in Clinical Infectious Diseases [1]. Because of our interest in the association of drug susceptibility testing (DST) results for firstand second-line drugs with treatment outcomes in patients with multidrugresistant (MDR) tuberculosis and extensively drug-resistant (XDR) tuberculosis, we carefully read the entire article. In this study, the investigators first performed a meta-analysis of 31 cohort studies of patients with MDR and XDR tuberculosis to assess the relationship between treatment outcomes and results of culturebased DST for pyrazinamide, ethambutol, and the second-line drugs. They reached an important conclusion that DST for ethambutol, pyrazinamide, and second-line