Facts about Multidrug-Resistant Tuberculosis (MDR-TB) and Extensively Drug-Resistant Tuberculosis (XDR-TB)
The emergence and spread of multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) are major medical and public problem, threatening the global health.
MDR-TB is defined as TB caused by bacteria that are resistant to at least rifampicin (RMP) and isoniazid (INH) - the two most important first-line anti-TB drugs. The annual global MDR-TB burden is estimated at around 425.000 cases or 5% of the global tuberculosis burden. Multidrug-resistant tuberculosis is a challenge to TB control due to its complex diagnostic and treatment requirements.
A fast and reliable resistance testing is essential to cut transmission paths and to change treatment to effective antibiotics of the second line. Treatment for MDR-TB is cost-intensive, time-consuming (minimum 18 months) and must be undertaken by a physician experienced in therapy of MDR-TB.
XDR-TB is currently defined as TB caused by bacteria that are resistant to rifampicin and isoniazid as well as resistant to any one of the fluoroquinolones (e.g. ofloxacin and moxifloxacin) and to at least one of the injectable second-line drugs (capreomycin, viomycin, kanamycin or amikacin).
XDR-TB emerges like MDR-TB through mismanagement of treatment. XDR-TB is already spread throughout all regions of the world. In some countries more than 20% of all multidrug-resistant TB cases are XDR.
Treatment of XDR-TB is extremely difficult. Only a few drugs are available. However, they are less efficient in comparison to first-line drugs and have strong side effects. Consequently, the treatment of XDR-TB is complex and must be undertaken by an experienced physician with high experience. The period of therapy can take up to several years. The mortality rate is extremely high.
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