XDR TB is defined as

  •  MDR TB that is resistant to either one of the injectable second line drugs or second-line therapeutic fluoroquinolones
  •  MDR TB that also is resistant to fluoroquinolones and at least one of the three injectable second-line drugs used to treat TB (amikacin, kanamycin, or capreomycin)
  •  resistant to two most effective first-line therapeutic drugs, isoniazid and rifampin irrespective of resistance to any other drug
  •  Strain resistant to more than one drug (excluding co resistance to INH and rif)