XDR TB is a rare type of multi-drug-resistant TB that is resistant to isoniazid, rigampin, fluoroquinolone and at least one of three second-line injectable drugs (amikaxin, kanamycin or capreomycin). The remaining treatment options are less effective, have more side effects and more costly. It is of particular concern in people with HIV or other conditions that impair the immune system. XDR TB has been identified in every region of the world where there have been laboratory facilities capable of testing for it.