Antituberculosis Drug Reclassification for Proper Management of Rifampicin-resistant and Multidrug-resistant Tuberculosis

Abstract

Tuberculosis (TB) is a major infectious disease and increasing incidence of drug-resistant-TB is a serious threat to global TB control. Active TB disease in humans is caused mainly by Mycobacterium tuberculosis. Some disease cases are also caused by Mycobacterium africanum (mainly in Africa) and Mycobacterium bovis (due to consumption of unpasteurized milk), two other species belonging to the M. tuberculosis complex [1]. The infection is mainly acquired by inhalation of tubercle bacilli expectorated by pulmonary TB patients (open TB) during close human contact [1]. Primary infection either leads to clinically active TB disease or the host immune response arrests multiplication of M. tuberculosis. However, complete sterilization is achieved in some individuals only while few bacilli in other individuals escape killing, become dormant and persist in granulomatous lesions (latent TB infection) [1]. The latent infection may remain dormant for a long time or resuscitates to cause active TB, years to decades later, often due to weakening of the host immune response [1]. Nearly 25% of the world population is latently infected with tubercle bacilli and 5%-10% of the infected individuals will eventually develop active TB disease during their life-time [2]. Reactivation of latent infection is more frequent in people with immunodeficiencies, diabetes, other immunosuppressive conditions or co-infection with human immunodeficiency virus (HIV) [1]. Active TB disease in low TB incidence/high income countries mostly occurs in foreign-born individuals due to reactivation of latent infection while recent infection/re-infection is common in TB endemic countries [1,3].