Treatment for drug sensitive Tuberculosis is of a much longer duration than for other bacterial infections, with a full course of treatment lasting 6 months. Since the 1950s, the duration of TB treatment was repeatedly reduced through the introduction of new drugs. In 1950, 18 months of streptomycin, isoniazid and PAS were needed to cure the disease. This duration was reduced by the introduction of rifampicin and pyrazinamide to the 6 months regimen.
The current standard treatment consists of two months of four drugs (isoniazid, rifampicin, pyrazinamide, ethambutol) and four months of two drugs (isoniazid, rifampicin). It is highly effective and can cure up to 95% of all TB patients, if the full course of treatment is taken. However, in some settings up to one third of all TB patients do not complete their six months of treatment. This is due to the fact that most patients start feeling better long before the treatment is completed and therefore increasing the risk of treatment failure and/or subsequent relapse.
Furthermore, TB is increasingly becoming resistant to the current treatment, with multi-drug resistant TB (MDR-TB) and extensive drug resistant TB (XDR-TB) rates increasing worldwide. Treatment for these forms of disease is of long duration and poor efficacy, and success is only achieved in about two thirds of MDR-TB, and about half of XDR-TB cases.