Sekaggya-Wiltshire C, et al. - Researchers investigated how antituberculosis drug concentrations are associated with sputum conversion among patients coinfected with tuberculosis and human immunodeficiency virus (HIV) and receiving first-line antituberculosis drugs. They estimated first-line antituberculosis drug concentrations 1, 2, and 4 hours after drug intake at 2, 8, and 24 weeks of tuberculosis treatment among HIV-infected Ugandans with pulmonary tuberculosis. Outcomes suggest that low antituberculosis drug concentrations did not translate to a high proportion of patients with treatment failure, however, there was an association between low concentrations of rifampicin and isoniazid and delayed culture conversion that may have implications for tuberculosis transmission.