Mycobacterium tuberculosis having resistance to rifampicin, isoniazid, and pyrazinamide is described as -

Ans. is 'b' i.e., Multi drug resistant tuberculosis * Mycobacterium tuberculosis having resistance to rifampicin, isoniazid, and pyrazinamide falls in the category of Multidrug resistant tuberculosis (MDR-tb) as it shows resistance to two most effective first line drugs of tuberculosis i.e. isoniazid and rifampicin.Definitions fo drug-resistant tuberculosis* Drug-resistant tuberculosis: tuberculosis bcaused by an isolate of Mycobacterium tuberculosis that is resistant to at least 1 of the first-line antituberculosis drugs: isoniazid, rifampin, ethambutol, pyrazinamide, or streptomycin* Monoresistance: resistance to 1 antituberculosis medication.* Multidrug-resistant tuberculosis: tuberculosis caused by an isolate of M tuberculosis that is resistant to the 2 most effective first-line drugs-isoniazid rifampin-and possibly other antituberculosis drugs.* Extensively drug-resistant tuberculosis: multidrug-resistant tuberculosis that is also resistant to the most effective second-line drugs, fluoro-quinolones, and at least 1 of the 3 injectable second-line drugs used to treat tuberculosis (amikacin, kanamycin, or capreomycin) and, possibly, to other antituberculosis drugs.