The multidrug-resistant tuberculosis threat: old problems and new solutions

With more than 1 million deaths and 9 million estimated incident cases in 2013 tuberculosis represents one of the top clinical and public health priorities worldwide. The WHO estimated that 13% of the 9 million TB cases (1.1 million people) were HIV-infected, particularly in the WHO African Region, where 4 out of 5 of these cases are estimated to occur in 2013. Aim of the present contribution is to describe the global MDR-TB context, focusing on the problems related to its prevention, diagnosis and treatment. The administration of ethionamide/prothionamide, as well as ofloxacin or late-generation quinolones, pyrazinamide, and cycloserine was associated with a higher probability of treatment success, compared to failure, relapse and death. Unfortunately, the prescription of group 5 drugs (amoxicillin-clavulanate, clofazimine, clarithromycin, and thiacetazone), whose efficacy is unknown for Mycobacterium tuberculosis, did not demonstrate higher effectiveness in a subset of patients belonging to the pooled cohort. In this context, the need of new anti-TB drugs is obvious. After more than 40 years without new TB drugs, two new drugs (bedaquiline and delamanid) have been recently approved.