Diagnosis of Mycobacterium tuberculosis

Tuberculosis (TB), caused by the intracellular bacterium, Mycobacterium tuberculosis (Mtb), has been a major health concern since it plagued ancient Egypt 5 thousand years ago. TB infects 9 million people every year, most of them children (especially in endemic areas), and it leads to approximately 2 million deaths annually (World Health Organization [WHO], 2008; Kabra & Lodha, 2004; Marais & Pai, 2007). These numbers are expected to increase in the coming years because of (1) the AIDS pandemic—a high percentage of the patients with human immunodeficiency virus (HIV) are co-infected with Mtb, and (2) the emergence of drug-resistant strains of the TB organisms (Corbett et al., 2003; Raviglione, 2003; WHO, 1994). This alarming increase in morbidity and mortality highlights the need to strengthen control measures. Accurate and rapid diagnosis is essential for controlling the disease, yet the traditional tests for TB produce results that are either inaccurate or take too long to be definitive. A fast and reliable diagnostic method that could differentiate between active and latent TB infection is lacking as well.