Tuberculosis therapy: past, present and future.

The major historical landmarks of tuberculosis (TB) therapy include: the discovery of effective medications (streptomycin and para-aminosalicylic acid) in 1944; the revelation of "triple therapy" (streptomycin, para-aminosalicylic acid and isoniazid) in 1952, which assured cure; recognition in the 1970s that isoniazid and rifampin could reduce the duration of treatment from 18 to 9 months; and the observation in the 1980s that adding pyrazinamide to these drugs allowed cures in only 6 months. To combat noncompliance, intermittent regimens, twice or thrice weekly, have been proven to cure even far-advanced TB in as few as 62-78 encounters over 26 weeks. However, these regimens are not sufficiently short or convenient to facilitate effective treatment in resource-poor countries. Therefore, drug-resistant strains have emerged to threaten TB control in various areas of the world, including India, China, Russia and the former Soviet Union. For these reasons, it is vital that new medications are developed to shorten the duration of therapy, increase the dosing interval of intermittent regimens and replace agents lost to resistance. Other special considerations include identifying optimal therapy for persons with acquired immune deficiency syndrome, particularly noting the problems of drug/drug interactions for those receiving antiretroviral treatment. Finally, the Alchemist's Dream of tuberculosis should be pursued: modulating the immune response to shorten treatment and/or overcome drug resistance.