MDR tuberculosis is defined by -
Resistance to all first and second line anti-tubercular agents
Resistance to any three first line anti-tubercular agents
Resistance to all first line and any three classes of second line anti-tubercular agents
Resistance to isoniazid and rifampicin
Ans. is 'd' i.e., Resistance to isoniazid and rifampicin o MDR is defined as resistance INH and rifampicin with or without resistence to other drugs. XDR is defined as resistance to INH and rifampicin as well as to all fluoroquinolones and one of injectable drugs (capreomycin, kanamycin, amikacin).