World Health Organization recommended treatment regimens for previously treated patients, pending drug susceptibility testing (DST) results#
| Probability of MDR-TB | ||
| Medium or low¶ | High+ | |
| Drug | Duration months (phase) | |
| Ethambutol Isoniazid Pyrazinamide Rifampicin Streptomycin | 2 (intensive) | Empirical MDR-TB regimen |
| Ethambutol Isoniazid Pyrazinamide Rifampicin Ethambutol Isoniazid Rifampicin | 1 (intensive) | |
| To be changed once DST testing results are available | 5 (continuation) | To be changed once DST testing results are available |
MDR: multidrug-resistant; TB: tuberculosis. #: up to 2–3 months after the start of treatment; ¶: relapse, lost to follow-up; +: failure. Information from [17].