Treatment outcome of tuberculosis patients with MDR TB, pre-XDR TB, and XDR TB.

MDR = resistance to at least isoniazid and rifampin.
Simple MDR = resistance to only isoniazid and rifampin.
Pre-XDR = Pre-extensively drug resistant; the strain is resistant to isoniazid, rifampin, and a fluoroquinolone or any one of three second-line drugs (capreomycin, amikacin, kanamycin).
XDR = extensively drug resistant; the strain is resistant to isoniazid, rifampin and a fluoroquinolone and any one of three second-line drugs (capreomycin, amikacin, kanamycin).