The contribution of molecular biology in diagnosing tuberculosis and detecting antibiotic resistance

1 Tuberculosis throughout the world: a catastrophic situation With more than 2 million deaths and 9.4 million new cases per year (TB) remains a major public health concern throughout the world. Even though the World Health Organization (WHO) declared tuberculosis an international emergency in 1993, the situation has worsened due to the deterioration of socioeconomic conditions in many countries and the acquired immune deficiency syndrome (AIDS) pandemic, as well as the recent increase in drug-resistant tuberculosis strains. As an example, the prevalence of tuberculosis in Sub-Saharan Africa is estimated to have increased from 290/100,000 inhabitants in 2000 to 487/100,000 in 2004, with a mortality rate of 81/100,000 in 2004. Antibiotic-resistant strains of Mycobacterium tuberculosis are emerging due to a variety of reasons, such as the failure to identify resistance to a tuberculosis drug, interrupting treatment, omitting one or more antibiotics, suboptimal dosage, defective absorption, and not using enough active compounds on the strain. Thus, M. tuberculosis can become resistant to multiple antibiotics in the space of a few months. Susceptible bacteria are eliminated, giving way to resistant bacilli (Iseman 1993; Espinal, Dye 2005). In the 1990s, the United States reported strains of multidrug resistant (MDR) M. tuberculosis, defined as being resistant to isoniazid (INH) and rifampicin (RIF), which were responsible for serious epidemics with a high mortality rate, particularly in countries with a high rate of HIV (human immunodeficiency virus) and M. tuberculosis co-infection. Programs for fighting tuberculosis targeted the strains of tuberculosis resulting from these cases of co-infection (Moore M 2000; Corbett et al. 2003). In 1995, WHO established a Direct Observed Therapy Short course treatment program (DOTS) as a strategy for fighting tuberculosis. The program's goal was to ensure a cure rate of at least 85% and prevent further resistance to TB drugs. Unfortunately, the management of multi-drug resistant TB (MDR-TB) was left to the individual initiatives of already strained national programs, which lacked funding and specific WHO guidelines (Meya, McAdam 2007). In addition, although the tuberculosis rate fell in many countries, the total number of tuberculosis cases worldwide increased 1.8% between 1997 and 2000, and grew more than 6% in the former countries of the Soviet Union and Africa. In 1999, WHO put together a work group called "DOTS-plus" to oversee the use of antibiotics in treating drug-resistant tuberculosis (Bastian et al. 2000; WHO 2000b; Aziz et al. 2006). In 2000, WHO reported that there were drug-resistant