The Emerging Threat of Drug Resistant Tuberculosis

Abstract

An estimated 2 billion people, one-third of the global population, are infected with Mycobacterium tuberculosis (M.tb.), the bacterium that causes tuberculosis (TB) (Keshavjee and Seung, 2008). Spread through the air, this infectious disease kills 1.8 million people each year, or 4,500 each day (WHO, 2009a). TB is the leading killer of people with HIV, and it is also a disease of poverty—the vast majority of TB deaths occur in the developing world (WHO, 2009a). Exacerbating the devastation caused by TB is the growing threat of drug-resistant strains of the disease in many parts of the world. The development of drug resistance is a predictable, natural phenomenon that occurs when microbes adapt to survive in the presence of drug therapy (Nugent et al., 2010). Although antibiotics developed in the 1950s are effective against a large percentage of TB cases, resistance to these first-line therapies has developed over the years, resulting in the growing emergence of multidrug-resistant (MDR) and extensively drugresistant (XDR) TB, and even totally drug-resistant (TDR) TB (see Box 1-1 for definitions). In recognition