Treatment of Drug-Resistant Tuberculosis

Background The development of drug-resistant (DR) tuberculosis (TB) has become an increasing concern over the past few decades as the result of numerous factors, including widespread inappropriate or ineffectual use of antimicrobials to treat TB in the absence of drug-susceptibility testing (DST), lack of adequate uptake of systematic approaches to the treatment of drug-susceptible (DS) TB and DR-TB, introduction of human immunodeficiency virus (HIV) into areas with preexisting DR-TB, provider error, poor adherence to treatment, lack of availability of effective drugs, and transmission of DR strains.1 The World Health Organization (WHO) has estimated that annually there are over half a million new cases of rifampicin-resistant (RR) and multidrug-resistant (MDR) TB; that is, disease caused by Mycobacterium tuberculosis with resistance to isoniazid and rifampin. Globally, 156,000 persons with MDR-TB or RR-TB began treatment in 2018, but the latest data show that only 56% completed treatment successfully.2 Such poor treatment completion rates are the result of treatment for a longer duration with second-line anti-TB drugs (SLDs), which are less effective and have greater toxicity than the 4 drugs most commonly used to treat DS-TB. However, treatment performance has been shown to be much better when regimens are designed carefully and ensure good retention, under both trial and programmatic conditions.3,4