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Sulfamethoxazole


Mechanism of action:

Sulfamethoxazole is a sulfonamide antibiotic. Structurally, sulfamethoxazole resembles para-aminobenzoic acid (PABA), which is an essential precursor for bacterial folic acid synthesis. Sulfamethoxazole competitively binds to dihydropteroate synthase in place of para-aminobenzoic acid, thereby blocking the formation of dihydrofolic acid and ultimately interfering with bacterial nucleic acid synthesis.

Reference(s):

1. Kazanjian P et al. (1998). Pneumocystis carinii mutations associated with sulfa and sulfone prophylaxis failures in AIDS patients. AIDS. 


2. Khalil I et al. (2003). Dihydrofolate reductase and dihydropteroate synthase genotypes associated with in vitro resistance of Plasmodium falciparum to pyrimethamine, trimethoprim, sulfadoxine, and sulfamethoxazole. Am J Trop Med Hyg. 


3. Yun MK et al. (2012). Catalysis and sulfa drug resistance in dihydropteroate synthase. Science.

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