Which of the following is true regarding the mechanism of action of the medications listed?

A patient with multibacillary leprosy is on dapsone, clofazimine, and rifampin.

Which of the following is true regarding the mechanism of action of the medications listed?
A . Dapsone is bacteriostatic because of its inhibitory effects on dihydrofolate reductase
B . Dapsone is bacteriostatic because of its inhibitory effects on myeloperoxidase
C . Clofazimine is bactericidal by directly inhibiting bacterial DNA polymerase
D . Rifampin is bacteriostatic by inhibiting RNA synthesis by blocking DNA-dependent RNA polymerase
E . Rifampin is bactericidal by inhibiting RNA synthesis by blocking DNA-dependent RNA polymerase

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Answer: E

Explanation:

A, B C false C dapsone inhibits bacterial synthesis of dihydrofolic acid, via competition with para­aminobenzoate for the active site of dihydropteroate synthetase. Dapsone is both bacteriostatic and weakly bactericidal against M. leprae. Neither of the listed mechanisms are the cause of these effects. C C False C A substance with both anti-leprosy and anti-inflammatory activity, clofazimine is weakly bactericidal against M. leprae by binding to the guanine bases of bacterial DNA, not DNA polymerase directly. D C False C See below. E C True C Rifampin is bactericidal by inhibiting RNA synthesis by blocking DNA-dependent RNA polymerase.