<prompt> Duration of treatment for MDR TB ?8-12 months12-16 months16-24 months2-3 years  <response>: Ans. is c i.e., 16-24 months Multi drug resistance TB MDR TBis referred to resistance to isoniazid and rifampicin with or without resistance to other drugs. MDR-TB is classified as category IV under DOTS DOTS -PLUS Treatment of Category IV MDR-TB includes,- Intensive phase 4 months: KOCZEEt Continuation phase 12-18 months: OCEEt Total duration 16-24 months In general treatment of MDR -TB is based on sensitivity of drugs and 5 or 6 of the drugs should be chosen in following order of preference based on known sensitivity - An aminoglycoside amikacin or kanamycin or capreomycin Pyrazinamide Ethambutol Flouroquinolones. moxifloxacin preferred rifabutin cycloserine ethionamide PAS clarithromycin Linezolid IFN - a thioridazine. Extensive drug resistance TB XDR -- TB is referred to resistance to rifampicin and isoniazid as well as to quinolone and at least one of the following second line drug kanamycin, capreomycin or amikacin. XDR -- TB resistance to INH, rifampcin, Quinolone, and capreomycinkanamycin amikacin 