ABSTRACT
I. Introduction The need for new, improved drugs for the treatment of tuberculosis (TB) is growing ever more urgent. Although the treatment of active, drug-sensitive, pulmonary tuberculosis is potentially 95% to 98% effective under ideal conditions (1), cure rates in the field are often significantly lower (2), and recently identified extensively drug-resistant (XDR) strains of Mycobacterium tuberculosis (3) are only 50% to 70% curable under the best of conditions (4). In some situations, particularly in HIV-positive individuals, XDR-TB has been reported to be close to 100% incurable (5). NewTBdrugs and improvedTB treatment regimens are required to (i) shorten and simplify treatment of active, drug-sensitive disease; (ii) provide shorter, safer, more effective, and lower-cost treatment alternatives for multidrug-resistant (MDR) and XDR-TB; (iii) remove obstacles to effective treatment of TB inHIV-positive individuals; and (iv) shorten treatment of latent TB infection (LTBI). The following sections examine each of these pressing needs in turn.
