Sulfamethoxazole is an antibiotic. It is used for bacterial infections such as urinary tract infections, bronchitis, and prostatitis and is effective against both gram negative and positive bacteria such as Listeria monocytogenes and E. coli.
Sulfamethoxazole is a bacteriostatic antibacterial agent that interferes with folic acid synthesis in susceptible bacteria. Its broad spectrum of activity has been limited by the development of resistance.
Sulfamethoxazole and trimethoprim combination is used to treat infections such as urinary tract infections, middle ear infections (otitis media), bronchitis, traveler's diarrhea, and shigellosis (bacillary dysentery). This medicine is also used to prevent or treat Pneumocystis jiroveci pneumonia or Pneumocystis carinii pneumonia (PCP), a very serious kind of pneumonia.
Sulfamethoxazole is a sulfonamide bacteriostatic antibiotic that is most commonly used in combination with trimethoprim as the drug Bactrim. Sulfamethoxazole competitively inhibits dihydropteroate synthase preventing the formation of dihydropteroic acid, a precursor of folic acid which is required for bacterial growth.