Global Threats and the Control of Multidrug-Resistant Tuberculosis
About one-third of the world’s population has been infected with Mycobacterium tuberculosis. Active disease develops in about 9 million people per year, and tuberculosis is responsible for 2 million deaths per year. The disease caused by this bacterium, tuberculosis (TB), remains one of the leading causes of mortality caused by infection worldwide and is a major threat to global health. The situation of TB is recently exacerbated by the emergence of highly drug-resistant forms of the disease-causing pathogen and synergy with human immunodeficiency virus/acquired immune deficiency syndrome, which greatly increases the risk of latent M. tuberculosis infection progressing to active disease. Multidrug-resistant (MDR) tuberculosis is defined as disease caused by strains of M. tuberculosis that are at least resistant to isoniazid and rifampicin; extensively drug-resistant (XDR) tuberculosis refers to disease caused by MDR strains that are also resistant to any fluoroquinolone and any of the injectable drugs used in treatment with second-line anti-tuberculosis drugs (amikacin, capreomycin, and kanamycin). MDR- and XDR-TB are serious threats to the progress that has been made in the control of tuberculosis worldwide over the past decade. In this review, we focus on threats of MDR-TB and the research and development of improved diagnostics, new chemotherapeutic agents, and vaccine candidates for MDR-TB.