<prompt> Multi drug resistant tuberculosis is defined as resistance to?INH and PyrizinamideINH and RifampicinRifampicin and PyrizinamideResistance to all first line drugs  <response>: Ans. is b i.e., INH and Rifampicin o Multi-Drug Resistant Tuberculosis is defined by resistance to INH and Rifampicin.o Multi-Drug Resistant Tuberculosis MDR-TB is defined as disease caused by strain of M Tuberculosis that is resistant to both Isoniazid ONH and Rifampicin-the most efficacious of the first line Anti-TB drugs - Harrison 