Extensively Drug-Resistant (XDR) Tuberculosis: A Review

Extensively drug-resistant (XDR) tuberculosis is defined as disease caused by Mycobacterium tuberculosis with resistance to at least isoniazid and rifampicin, any fluoroquinolone, and at least one of three injectable secondline drugs (amikacin, capreomycin, or kanamycin). This definition in immensely valuable for more uniform surveillance in varied international settings. The prevalence of tuberculosis drug resistance has risen to the highest rate ever recorded. Although the gold standard for drugsusceptibility testing has been the agar proportion method; due to it’s time consumption, more sensitive, specific and rapid diagnostic tests are required. It is difficult to differentiate XDR tuberculosis from non-XDR tuberculosis