Regimens to treat multidrug-resistant tuberculosis: past, present and future perspectives.

Over the past few decades, treatment of multidrug-resistant (MDR)/extensively drug-resistant (XDR) tuberculosis (TB) has been challenging because of its prolonged duration (up to 20-24 months), toxicity, costs and sub-optimal outcomes.After over 40 years of neglect, two new drugs (bedaquiline and delamanid) have been made available to manage difficult-to-treat MDR-/XDR-TB cases. World Health Organization (WHO) guidelines published in March 2019 endorsed the possibility of treating MDR-TB patients with a full oral regimen, following previous guidelines published in 2016 which launched a shorter regimen lasting 9-10 months.The objectives of this article are to review the main achievements in MDR-TB treatment through the description of the existing WHO strategies, to discuss the main ongoing trials and to shed light on potential future scenarios and revised definitions necessary to manage drug-resistant TB.