Inhibitors of Nucleic Acid Synthesis

Question 1

Sulfamethoxazole (SMX), sulfisoxazole, sulfadiazine

Answer 1

Mechanism: Inhibit Dihydropterote synthetase, stops folic acid synthesis
Targets: Nocardia, Listeria, Gram -, Gram +, fungus, and Protoza
Side Effects: hypersensitivity, hemolysis in G6PD deficiency, phototoxicity

Question 2

Trimethoprim and Pyrimethamine

Answer 2

Mechanism: Inhibit Dihydrofolate reductase
Targets: UTI, shigella, salmonella, PCP
Side effects: megoblastic anemia, leukopenia

Question 3

Ciprofloxacin, levofloxacin, ends in -floxacins

Answer 3

Fluoroquinolones
Mechanism: Inhibit DNA gyrase (topoisomerase II) and topoisomerase IV. Bactericidal. Must not be
taken with antacids.
Targets: Gram - rod of urinary, GI tracts, neisseria, some gram +
Side Effect: GI upset, skin rashes, prolonged QT, tendonitis.
Resistance: Mutation in DNA gyrase and efflux pumps