This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
The drug inhibiting DNA-dependent RNA polymerase in Mycobacteria is - 
Select and explain. 
A. INH, B. Rifampicin, C. Ciprofloxacin, D. Ethionamide
B: Rifampicin
Answer: B: Rifampicin 
Explanation: Ans. is 'b' i.e., Rifampicin Mechanism of action of impoant antitubercular drugs o Rifampicin --> Inhibits DNA dependent RNA synthesis by inhibiting RNA polymerase. o INH --> Inhibits synthesis of mycolic acid which is a component of mycobacterial cell wall. o Pyrazinamide --> Inhibits synthesis of mycolic acid. o Streptomycin --> Inhibits protein synthesis (translation). o Ethambutol --> Inhibits incorporation ofmycolic acid into bacterial cell wall by inhibiting arbinosyltransferase.