Staphylococcus aureus DHFR in complex with NADPH and<unk>  PDB entry<unk>  binds to dihydrofolate reductase and inhibits the reduction of dihydrofolic acid (DHF) to tetrahydrofolic acid (THF). THF is an essential precursor in the thymidine synthesis pathway and interference with this pathway inhibits bacterial DNA synthesis.<unk> 's affinity for bacterial dihydrofolate reductase is several thousand times greater than its affinity for human dihydrofolate reductase. Sulfamethoxazole inhibits dihydropteroate synthase, an enzyme involved further upstream in the same pathway.<unk>  and sulfamethoxazole are commonly used in combination due to possible synergistic effects, and reduced development of resistance. This benefit has been questioned. upright=1.25
Trimethoprim
Sulfamethoxazole
Moxifloxacin
Enrofloxacin
Phenoxymethylpenicillin
Doxycycline
Tetracycline
Minocycline