Drug-resistant tuberculosis threatens efforts to control this common disease. It investigated 35 countries participating in the World Health Organization International Union against Tuberculosis and Lung Disease Global Project on Anti-Tuberculosis Drug Resistance Surveillance. Over the past 50 years, the proliferation of antimicrobial agents for use in humans and animals has placed an unprecedented selective pressure on micro-organisms. Drug resistance in patients with Mycobacterium tuberculosis infection became apparent soon after the introduction of effective anti-tuberculosis agents. Spontaneous mutations leading to drug resistance occur rarely in Mycobacterium tuberculosis , and multidrug anti-tuberculous regimens can prevent the emergence of clinical drug resistance.
Drug resistance is a potential threat to tuberculosis control programmes throughout the world.
The magnitude of the problem of resistance to anti-tuberculosis drugs worldwide is currently not known. However, many of these studies were not based on representative samples or failed to distinguish between patients who had received previous treatment for tuberculosis and those who had not. Furthermore, there was no consensus on definitions, and laboratory results were not standardized. These limitations prevented an adequate assess-ment of the extent of the problem throughout the world and precluded meaningful comparisons among countries. The purpose of the project, which is based on a network of reference laboratories, is to measure the prevalence of resistance to anti-tuberculosis drugs in countries throughout the world with the use of standardized methods.