A child with complicated .

Tuberculosis (TB) is one of the leading causes of morbidity and mortality worldwide, with ever increasing resistance to commonly used antituberculous drugs. Drug-resistant TB was recognized shortly after the introduction of an effective therapy in the late 1940s, the use of streptomycin, which was the first widely used antituberculosis drug. Patients who received this drug usually had marked and rapid clinical improvement, but treatment failures were common after the first three months of therapy.