Multi Drug Resistant (MDR) and Extensively Resistant (XDR) Tuberculosis

Abstract

Multi drug resistant tuberculosis (MDR-TB) is defined as tuberculosis that is resistant to at least isoniazid and rifampicin, the two most powerful first-line anti-TB drugs. Extensively drug resistant tuberculosis (XDR-TB) is defined as tuberculosis that is resistant to resistant to isoniazid and rifampin and to any fluoroquinolone and at least one of three injectable second-line drugs (namely, amikacin, kanamicin, or capreomycin). MDR-TB and XDR- TB are great dangers that threaten the public health. XDR-TB has been reported from many countries including the United States. In Turkey, among newly diagnosedcases, it was reported that the number of MDR-TB patients was 101 (3.1%), MDR-TB rate in the retreatment cases was 17.7% (90 patients), and MDR-TB rate in all cases was 5.1 (191 patients) in 2005. The percentages were calculated through the number of patients who were tested in terms of susceptibility for both isoniazide and rifampin. In 2009, it was reported that the number of MDR-TB patients was 99 (2.7%) among newly diagnosed cases, it was 123 (20.5 %) in the retreatment cases and the total number of MDRTB cases was 222 (5.1%). The first patient with XDR-TB was identified in 2010 in Turkey. Diagnosis of XDR TB takes several weeks by using conventional culture-based methods, although (however) some molecular test can detect it rapidly. Treatment of XDR-TB patients is difficult and usually requiring at least 18-24 months of four to six second-line anti-TB drugs. The success rate with the treatment is about 30-50%, and mortality rate is higher in HIV-infected patients. Prevention of contact to XDR-TB patients is more complicated by the lack of a proven effective preventive treatment for XDR latent tuberculosis infection. Rapid diagnostic tests and new anti-TB drugs are needed to control the spread of this worldwide public health problem.