Which of the followig antitubercular drug acts by inhibiting bacterial DNA dependent RNA polymerase?

Ans. D. Rifampicin. (Ref. KDT 6th/pg. 741, 745).KDT 6th/pg. 741......."Rifampicin inhibits DNA dependent RNA synthesis. Probably the basis of selective toxicity is that mammalian RNA polymerase does not avidly bind rifampin". ANTIBIOTICMECHANISM OF ACTIONAminoglycosides* Inhibit protein synthesis by binding to a portion of the bacterial ribosome. Most of them are bacteriocidal (i.e., cause bacterial cell death).Bacitracin* Inhibits cell wall production by blocking the step in the process (recycling of the membrane lipid carrier) which is needed to add on new cell wall subunits.Beta-lactam antibiotics* A name for the group of antibiotics which contain a specific chemical structure (i.e., a beta-lactam ring). This includes penicillins, cephalosporins, carbapenems and monobactams.Cephalosporins* Similar to penicillins in their mode of action but they treat a broader range of bacterial infections. They have structural similarities to penicillins and many people with allergies to penicillins also have allergic reactions to cephalosporins.Chloramphenicol* Inhibits protein synthesis by binding to a subunit of bacterial ribosomes (50S).Glycopeptides (e.g., vancomycin)* Interferes with cell wall development by blocking the attachment of new cell wall subunits (muramyl pentapeptides).Macrolides (e.g., erythromycin) and Lincosamides (e.g., clindamycin)* inhibiting bacterial protein synthesis. It combines with 50S ribosome subunits and interferes with 'translocation'.Penicillins* Inhibits formation of the bacterial cell wall by blocking cross-linking of the cell wall structure. The cell wall is a needed protective casing for the bacterial cell.Quinolones* Blocks DNA synthesis by inhibiting one of the enzymes (DNA gyrase) needed in this process.Rifampin* Inhibits RNA synthesis by inhibiting one of the enzymes (DNA-dependent RNA polymerase) needed in this process. RNA is needed to make proteins.Tetracyclines* Inhibit protein synthesis by binding to the subunit of the bacterial ribosome (30S subunit).Trimethoprim and Sulfonamides* Blocks cell metabolism by inhibiting enzymes which are needed in the biosynthesis of folic acid which is a necessary cell compound.