Extensively Drug-Resistant Tuberculosis (XDR-TB)

Extensively Drug-Resistant Tuberculosis (XDR-TB) is caused by bacteria that are resistant to first-line anti-TB drugs (isoniazid and rifampicin) and second-line drugs: fluoroquinolones and at least one of three injectable drugs (i.e., amikacin, kanamycin, or capreomycin).

Rare but found in every region of the globe, XDR-TB bacteria develop when first-line and second-line anti-TB drugs are misused or mismanaged (drugs are taken in the wrong combination, are fewer than prescribed or taken in insufficient doses or insufficient time).

Transmission of the XDR-TB bacteria is person-to-person through sneezing, coughing or merely talking. A person acquiring the bacteria may become diseased with XDR-TB depending on the amount of exposure to the bacteria and the strength of the patient's immune system. Individuals with HIV/AIDS are at greater risk of becoming ill.

Data indicate that the cure rate for XDR-TB is dismal. Treatment options are severely limited. Under the best medical care, only about half of affected people survive. Consequently, there is an urgent need for new drugs.