Twenty years of global surveillance of antituberculosis-drug resistance

Antimicrobial resistance represents a major threat to global health and security. In 2014, the World Health Assembly called on all nations and the international community to take every necessary measure to control it, including surveillance of its emergence and spread.1 The development of drug resistance in Mycobacterium tuberculosis was first documented in the late 1940s, soon after antibiotic therapy was introduced for tuberculosis treatment.2 It quickly became obvious that combination chemotherapy could prevent the emergence of drug resistance3 and that patients infected with drug-resistant strains were less likely to be cured.4 Nevertheless, it was only in the early 1990s that drugresistant tuberculosis began to receive global attention as a public health threat. This coincided with the detection of outbreaks of multidrugresistant (MDR) tuberculosis (defined as resistance to at least rifampin and isoniazid) that were associated with high mortality among patients coinfected with the human immunodeficiency virus (HIV).5-8 The urgent need for a global mechanism to monitor the emergence and spread of resistance to antituberculosis drugs became clear. In 1994, the Global Tuberculosis Program of the World Health Organization (WHO), with the support of the International Union against Tuberculosis and Lung Disease (the Union), established the Global Project on Anti-Tuberculosis Drug Resistance Surveillance (hereafter referred to as “the project”) to measure the magnitude of drug resistance and to monitor trends. This project remains the oldest and largest initiative on the surveillance of antimicrobial resistance in the world.9 In this article, we describe the history of global surveillance of drug resistance in tuberculosis and discuss methods for surveillance, the quality of available data, the key achievements and findings to date, the main challenges that remain, and future directions.