Treatment of multidrug-resistant (MDR) tuberculosis (TB) (defined as resistance to at least isoniazid and rifampicin, two core first-line drugs for TB treatment) and extensively drug-resistant (XDR)-TB (defined as resistance to isoniazid and rifampicin plus any fluoroquinolone and at least one of the injectable drugs amikacin, capreomycin or kanamycin) are a challenge for both clinicians and public health specialists [1–5]. Treatment outcomes of difficult-to-treat MDR-TB cases (e.g. those with an extensive resistance pattern) are still unsatisfactory, adverse events frequent and severe, and the necessary drugs expensive [6].