Resistance to at least INH & rifampicin +/- other drugs
B
Resistance to any of the 3 first line drugs
C
Resistance to all 1st line drugs & any 3 second line injectable drugs
D
Resistance to at least INH & rifampicin + any quinolones + at least 1 injectable 2nd line drug
High-Yield Explanation
XDR -TB - resistant to - (1) INH & rifampicin (2) Any fluoroquinolone (3) 1 of 3 injectable drug (Amikacin, kanamycin or Capreomycin) MDR-TB - Resistance to INH & Rifampicin.