Characteristics of tuberculosis patients by drug resistance group, Shanghai, March 2004–November 2007.

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 three of the second-line drugs (capreomycin, amikacin, kanamycin).XDR = extensively drug resistant; the strain is resistant to isoniazid, rifampin and a fluoroquinolone and any of three of the second-line drugs (capreomycin, amikacin, kanamycin).